We benchmark exchange-correlation functionals for the calculation of fundamental band gaps of inorganic nitrides. These include conventional functionals such as the local density approximation (LDA), the generalized-gradient (Perdew-Burke-Ernzerhof) approximation (PBE), simple Slater exchange functionals (SLOC), specialized LDA/GGA-derived high local exchange (HLE16) and Armiento-Kümmel semilocal (AK13) functionals, meta-GGA functionals including TASK, the modified Becke-Johnson functional (mBJ), and Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional, as well as quasiparticle GW theory. Since inorganic nitrides remain strongly under-represented in previous extensive benchmark studies, the current subdatabase contributes towards building a future large-scale balanced materials compilation of band gaps to benchmark theory. From a literature survey, we carefully collect 25 binary and 11 ternary nitrides with a focus on semiconductors spanning the periodic table, including ionic Li3N, antibixbyite-structured X3N2 (X = Be, Mg, Ca), early transition metals and lanthanides (e.g., ScN, YN, and LaN), ultrahard Th3P4-type structured M3N4 (M = Zr, Hf) compounds, promising photocatalysts Ta3N5, different polymorphs of III-V reference covalent nitrides (BN, AlN, GaN), and many M3N4 polymorphs (M = C, Si, and Ge) such as spinel-structured phases. Consistent with previous extensive benchmark tests, conventional LDA/PBE unsystematically largely underestimate band gaps with mean absolute errors (MAE) of >1.0 eV and mean absolute percentage errors (MAPE) of about 50%. Simple Slater exchange functional, SLOC, the GGA-derived AK13LDA and HLE16 functionals show improvement over LDA/PBE with MAE of 0.5-0.6 eV (MAPE ∼ 20-25%) with mBJ and HSE06 being the most accurate, with MAE = 0.30 and 0.28 eV (MAPE 12.1% and 11.1%), respectively. Strategies for the development of machine learning and the choice of appropriate exchange-correlation functionals for high-throughput large-scale material screening are discussed in light of these results.

Abstract This study presents a comprehensive density functional theory investigation into the structural, electronic, and optical properties of inorganic halide perovskites with the general formula CsPbBr3–yXy (where X = I, Cl, F; and y = 0, 1, 2, 3). Using the Vienna Ab initio Simulation Package, electronic band structures were calculated employing a hierarchy of functionals: the generalized gradient approximation, Tran-Blaha-modified Becke-Johnson (TB-mBJ), TB-mBJ combined with spin–orbit coupling, and the hybrid HSE06 functional. Structural analysis confirms that substituting bromine with smaller halides such as fluorine (F) and chlorine (Cl) contracts the lattice, whereas iodine (I) substitution leads to lattice expansion, a trend consistent with the relative ionic radii. The results reveal systematic trends in bandgap tuning; incorporation of F and Cl widens the band gap, whereas I substitution narrows it. These changes are attributed to shifts in orbital interactions and varying electronegativities. Optical calculations demonstrate that F and Cl substitution decreases the low-energy electronic polarizability, yielding lower static real dielectric constants, indicating reduced electronic polarizability favorable for wide bandgap and UV-reflective coating components, whereas increasing I concentration raises the refractive index and stretches optical absorption deep into the visible range, matching solar illumination requirements. Spectroscopic limited maximum efficiency analysis of ten distinct compositions identifies CsPbI3 as the premier candidate, yielding a maximum theoretical spectroscopic efficiency of approximately 31% under radiative limits. These findings underscore halide substitution as an effective strategy for engineering the optoelectronic behavior of CsPbBr3-based perovskites for next-generation energy applications.

Ab initio molecular dynamics (AIMD) simulations within the NVT ensemble using the Nos & eacute; thermostat along with density functional theory (DFT) calculations to investigate the structural, dynamic, thermodynamic, and electronic properties of a 108-atoms of Mo- and Mo, X-doped (X = S, Se, Te) anatase TiO2 systems at 300, 450, and 600 K. The standard GGA + U bandgap of pure anatase TiO2 (3.01 eV) is reduced to 0.99 eV (Mo), 1.52 eV (Mo, S), 1.68 eV (Mo, Se), and 1.43 eV (Mo, Te) due to the formation of mid-gap states and enhanced orbital hybridization, suggesting improved visible-light absorption. Our results show that Mo doping alone induces thermal and energetic instabilities, whereas co-doping with chalcogens (S, Se, and Te) progressively enhances lattice stability, with Mo, Te co-doping exhibiting thermal behaviour closest to that of pure TiO2. For the 48-atom models, optical property calculations reveal that Mo doping and Mo, X (X = S, Se, Te) co-doping strongly shift absorption from the ultraviolet into the visible and infrared regions. The co-doped systems exhibit enhanced absorption coefficients and lower reflectivity in the visible range, indicating superior light-harvesting capability, with the optical response red-shifting progressively as the anion size increases from S to Se to Te. AIMD simulations show that Mo-doped anatase, TiO2 introduces local lattice rigidity but results in reduced thermal stability under finite-temperature conditions. Chalcogen co-doping (S, Se, and Te) enhances atomic mobility while improving overall thermal stability during AIMD simulations. Notably, Mo, Te- doped TiO2 exhibits high thermal stability despite larger atomic displacements, indicating that stability is achieved through efficient energy dissipation via lattice flexibility. Radial distribution function analysis confirms that all systems retain a well-defined local Ti-O bonding environment, with no significant bond-length fluctuations or structural disorder, even in the presence of chalcogen co-doping.

This study employs density functional theory (DFT) to investigate the electronic and optical properties of molybdenum (Mo) and chalcogen (S, Se, Te) co-doped anatase TiO2. Two co-doping configurations were examined: Model 1, where the dopants are adjacent, and Model 2, where the dopants are farther apart. The incorporation of Mo into anatase TiO2 resulted in a significant bandgap reduction, lowering it from 3.22 eV (pure TiO2) to range of 2.52–0.68 eV, depending on the specific doping model. The introduction of Mo-4d states below the conduction band led to a shift in the Fermi level from the top of the valence band to the bottom of the conduction band, confirming the n-type doping characteristics of Mo in TiO2. Chalcogen doping introduced isolated electronic states from Te-5p, S-3p, and Se-4p located above the valence band maximum, further reducing the bandgap. Among the examined configurations, Mo–S co-doping in Model 1 exhibited most optimal structural stability structure with the fewer impurity states, enhancing photocatalytic efficiency by reducing charge recombination. With the exception of Mo–Te co-doping, all co-doped systems demonstrated strong oxidation power under visible light, making Mo-S and Mo-Se co-doped TiO2 promising candidates for oxidation-driven photocatalysis. However, their limited reduction ability suggests they may be less suitable for water-splitting applications. The study also revealed that dopant positioning significantly influences charge transfer and optoelectronic properties. Model 1 favored localized electron density and weaker magnetization, while Model 2 exhibited delocalized charge density and stronger magnetization. These findings underscore the critical role of dopant arrangement in optimizing TiO2-based photocatalysts for solar energy applications.

Molybdenum ditelluride (MoTe2), a key member of the transition metal dichalcogenides (TMDCs) family, holds significant potential for applications in electronics, energy storage, and catalysis. Despite its importance, the range of MoTe2 structural forms that has been explored is still limited. The primary aim of this research is to identify new stable MoTe2 polymorphs that may exist under zero-temperature and zero-pressure conditions. This study offers an in-depth analysis of 11 different structural variations (polymorphs) of MoTe2 using advanced computational methods based on density functional theory (DFT). By employing the Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional, accurate calculations of electronic properties, such as band structure, are achieved. Bonding analysis, including charge density and electron localization, reveals consistent covalent interactions across the hexagonal and trigonal forms of MoTe2. The study also assesses the mechanical stability of these polymorphs using elastic constants, identifying both stable and metastable forms. Additionally, phonon and thermal properties, including heat capacity and entropy, are calculated for all dynamically stable polymorphs. Raman and infrared spectra provide insights into their distinct vibrational modes. These findings help distinguish structural attributes relevant to layer-specific applications. This comprehensive investigation of MoTe2 polymorphs uncovers new stable structures and provides crucial insights for their potential use in technological applications.

The electrochemical urea oxidation reaction (UOR) is substantiated as a promising pathway for transforming waste into renewable power. Hollow ball‐like architectures composed of 3D carbon shell‐encased Ni–Cu nanoparticles in multi‐walled carbon nanotubes (Ni x ‐Cu y /MWCNTs) have been synthesized, utilizing a bimetallic organic framework as a soft template in conjunction with chemical vapor deposition. The configurational and electronic traits of the as‐formulated catalysts and their impact on charge‐transfer processes are elucidated with density functional theory, and their influence on UOR kinetics is then explicated with various electrochemical techniques. The hierarchical porous hollow spherical bundles of Ni x ‐Cu y /MWCNTs accelerate urea utilization efficacy, as their interior and exterior surfaces are exposed to urea fuel. The synergistic interaction between bimetallic nanoparticles and graphitic carbon helps enhance the electron conduction pathways, electrocatalytic activity, and anti‐poisoning ability toward UOR. Compared to commercial Ni/C, the Ni x ‐Cu y /MWCNTs catalyst enables direct urea fuel cells (DUFC) with a high‐power density (47.3 mW cm −2 ) and longevity (200 h), benefiting from the energetically favored oxidation of UOR intermediates and suppressed N─C bond cleavage facilitated by the surface and interstitial vacancies in Ni x ‐Cu y /MWCNTs. Moreover, 32.7 mW cm −2 along with resilience against human urine fuel is achieved in DUFC, opening up research endeavors in sustainable energy development.

This study presents a first-principles investigation into the high-pressure studies of cesium lead fluoride (CsPbF3) polymorph using the Vienna ab initio simulation package (VASP). The CsPbF3 with Pm3̅m symmetry undergoes a pressure-induced structural transition, resulting in two distinct phases: R3̅c and Pnma. The structural stability, electronic structure, and optical properties of the three polymorphs of CsPbF3 (Pm3̅m, R3̅c and Pnma) are investigated using the plane wave pseudopotential method within the framework of density functional theory (DFT). The elastic constants and moduli of these polymorphs were computed and the result confirms that all are mechanically stable. Electronic band structure calculations indicate that all three CsPbF3 polymorphs exhibit semiconducting properties with a wide band gap (3-5 eV). The Pm3̅m, R3̅c form of CsPbF3 has a direct band gap while Pnma form has an indirect band gap. The mechanical stability and optical properties of the R3̅c and the Pnma phase of CsPbF3 have not been reported in the existing literature. By addressing this gap, this research contributes valuable data and sets the stage for future studies that explore these polymorphs in greater detail and their potential in advanced technological applications.

The Fe1+ySe1-xTex family of iron-based superconductors are extensively investigated for their unconventional nature of superconductivity, which arises from a complex interplay of spin and orbital ordering. At ambient conditions, Fe1.09Se0.55Te0.45 exhibits a superconducting transition below T-c similar to 14 K and a nematic ordering accompanied by a tetragonal to orthorhombic structural change at (T-s) which is marked by a sign change of Hall coefficient (R-H) from positive to negative. In addition, the normal state resistivity follows a -log(T) increase with decreasing temperature due to the presence of excess Fe impurity acting as Kondo scattering centre. In this work, we investigate the evolution of superconducting and normal state properties of Fe1.09Se0.55Te0.45, a member of the Fe1+ySe1-xTex family, under hydrostatic pressure (P) using magneto-transport, dc magnetization and complementary first-principles band structure calculations. With applied P, the superconducting T-c reveals a dome-like shape, reaching a maximum T-c similar to 19.9 K at critical pressure P-c similar to 3.3 GPa. Simultaneously, with increasing pressure, both the -log(T) resistivity increase and T-s are gradually suppressed. Near P-c, T-s almost disappears, while the -log(T) resistivity increase persist beyond P-c up to 5 GPa and a Fermi liquid like behaviour emerges around 8 GPa. Furthermore, the band structure calculations suggest a pressure-induced structural change from orthorhombic to monoclinic symmetry near P-c. The nontrivial nature is evidenced by the effects of high pressure on the charge carrier balance, phase transition and superconductivity in Fe1.09Se0.55Te0.45. This nontrivial superconductivity is strongly linked to the significant normal state that arises from the connection between Fermi surface reconstruction and structural phase transitions.

The importance of advanced materials like zirconium dioxide (ZrO2) in diverse medical, industrial, and technological contexts is underscored by contemporary technology. ZrO2 ' s unique combination of properties renders it indispensable for a broad spectrum of applications, suggesting its enduring importance. This study presents the very first investigation into the physical properties, structural stability, and ground-state characteristics of sixteen distinct ZrO2 polymorphs through the application of density functional theory (DFT). Motivated by the potential of ZrO2 polymorphs to substitute for SiO2, we conducted calculations to ascertain their dielectric properties. A comprehensive analysis was conducted on all structural features, and their stability was assessed. ZrO2 polymorphs exhibit a wide bandgap with the type of bandgap also examined. Calculated zone-center phonon frequencies demonstrate the dynamical stability of ZrO2, with existing polymorphs showing strong agreement with experimental frequencies, particularly within the monoclinic polymorph. Raman and infrared (IR) spectra of ZrO2 polymorphs were simulated using density functional perturbation theory. ZrO2 demonstrates notable mechanical stability, as evidenced by calculated hardness (moduli), ductility, improved ductility, and higher elasticity. Calculated optical properties, including the dielectric constant and refractive index of ZrO2 polymorphs, play a pivotal role in optimizing their performance in various applications such as optoelectronic devices and antireflective materials.

This study presents the first comprehensive first-principles investigation of the structural, dynamical, mechanical, electronic, and optical properties of MLiZnS2 (M = Na, K, Rb, and Cs), a new class of layered quaternary chalcogenides experimentally synthesized but not theoretically explored in detail. Density functional theory (DFT) calculations reveal a systematic phase transition from trigonal (NaLiZnS2) to tetragonal (K, Rb, and Cs analogues), driven by the ionic radius of the A-site cation. Phonon spectra confirm the dynamical stability of all equilibrium phases, while elastic constants satisfy Born criteria, verifying the mechanical stability (except tetragonal NaLiZnS2). Hybrid functional (HSE06) bandgaps (2.9-3.6 eV) align with related experimental trends, highlighting their suitability for optoelectronic applications. Optical analysis indicates low reflectivity, high absorption in the UV-visible range, and refractive indices compatible with antireflection coatings in photovoltaics. Electronic structures show flat valence bands and phonon gaps linked to high hole mobility and reduced thermal conductivity, suggesting prospects for spintronics and thermoelectrics. This work establishes MLiZnS2 as a promising platform for photovoltaic and multifunctional energy materials, bridging experimental synthesis and computational insights to guide future studies.

In response to the growing need for sustainable and autonomous sensing technologies driven by wearable electronics and the internet of things, triboelectric nanogenerators (TENGs) have gained attention as promising solutions for self-powered sensors and micro-energy harvesters. In this report a novel tribopositive material based on NiCo-Prussian blue analogue (NiCo-PBA), as tribopositive layer in a TENG device (NCP-TENG) against a PTFE tribonegative counterpart. The NCP-TENG delivers an impressive power density of 341.67 mW/m2, demonstrating its potential as a self-sustainable electrical energy source for powering microelectronic devices such as calculator, stop-watch and LEDs. To gain insights into the charge transfer mechanism, calculations based on density functional theory (DFT) were carried out, showing that the Co site in the NiCo-PBA possesses a stronger tribopositive nature than Ni site, thereby enabling more effective charge transfer to PTFE. Additionally, more charge accumulation was notably observed at the carbon site of PTFE, further corroborating the charge flow direction from PBA to PTFE. The multifunctional capability of NCP-TENG was further demonstrated through its use as a by its application as a self-powered sensor for detecting acetaminophen, delivering a high sensitivity of 6.09 nA mu M- 1 cm- 2 and remarkable limit of detection of 0.197 mu M.

This study provides a comprehensive analysis of the electronic and optical properties of low-energy gallium oxide (Ga2O3) polytypes not considered earlier. Among these polytypes, the monoclinic structure (β-Ga2O3) holds significant relevance for both research and practical applications due to its superior stability under typical conditions. The primary aim of this research is to identify new and stable Ga2O3 polytypes that may exist under zero-temperature and zero-pressure conditions. To achieve this objective, we employ the VASP code to investigate electrical and optical properties, as well as stability assessments. Additionally, we examine phonon and thermal properties, including heat capacity, for all polytypes. This study also encompasses the computation of full elastic tensors and elastic moduli for all polytypes at 0 K, with Poisson's and Pugh's ratios confirming their ductile nature. Furthermore, we present the first ever report on the Raman- and infrared (IR)-active modes of these stable Ga2O3 polytypes. Our findings reveal that these mechanically and dynamically stable Ga2O3 polytypes exhibit semiconductive properties, as evidenced by electronic band structure investigations. This research offers valuable insights into the optical characteristics of Ga2O3 polytypes with potential applications spanning various fields.

By combining experimental and computational studies, the orthorhombic stannide CeMgSn with a TiNiSi-type structure has been characterized as a potential hydrogen storage material. Experimental studies of the formed monohydride CeMgSnH including hydrogen absorption-desorption, thermal desorption spectroscopy, synchrotron and neutron powder diffraction (298 and 2 K), magnetization, and Sn-119 M & ouml;ssbauer spectroscopic measurements are discussed in parallel with ab initio electronic structure calculations. A small, 1.27 vol %, expansion of the unit cell of CeMgSn during its transformation into a thermally stable CeMgSnH monohydride is caused by an ordered insertion of H atoms into half of the available Ce3Mg tetrahedral interstices leaving the CeMg3 tetrahedra unoccupied. The bonding in CeMgSnH is dominated by strong Ce-Sn and Mg-Sn interactions which are almost not altered by hydrogenation, whereas the H atoms carry a small negative charge and show bonding interactions with Ce and Mg. Hydrogenation causes a conversion of the antiferromagnetic CeMgSn into ferromagnetic CeMgSnH with the Ce moments aligned along [001] with a magnetic moment of 1.4(3) mu(B). The Sn-119 isomer shifts and the values of quadrupole splitting in the M & ouml;ssbauer spectra suggest a similar s-electron density distribution for the Ce- and La-containing REMgSnH monohydrides.

In the present study, we demonstrated a cost-effective chia seed-based triboelectric nanogenerator (C-TENG), leveraging the triboelectric properties of chia seeds. The C-TENGs are fabricated with a simple architecture, establishing adaptability, cost effectiveness, and versatility as an ecofriendly harvester of mechanical energy. The C-TENG exhibits open- circuit voltage and short-circuit currents on the order of 501.8 V and 24.5 mu A, respectively. Load matching reveals the maximum power density output at a load resistance of 5 M Omega, reaching 290 mW/m2. The cycle test over 3400 cycles confirms the C-TENG's stability. Furthermore, its capability to charge capacitors with different capacitances highlights its potential as a biomechanical energy harvester. The prototype device for evaluating the real-time applications demonstrated the C-TENG's, ability to illuminate LEDs, power a calculator, capture kinetic energy during walking, and transducer as an electronic switch. This investigation pioneered the exploration of chia seeds in TENGs, presenting a sustainable and efficient solution for self-powered microelectronic devices. The electron affinity of materials has been analyzed through inter- and intramolecular charge distribution using density functional theory. The direction of charge transfer was estimated through frontier molecular orbital analysis supported by the experimental findings of triboelectrification via contact separation from the molecule to polytetrafluoroethylene (PTFE).

Here we present the optoelectronic properties of pure inorganic lead-free halide perovskites in the form of Cs2AgBiX6 (X = Br, Cl, F, I) using the density functional theory calculations on cubic phase (Fm (3) over bar m) and tetragonal phase (I4/m). First, all the structures of the two phases were optimized at the PBE level. Structural, electronic, optical properties, phonon, and thermal properties of Cs2AgBiX6 in cubic (Fm (3) over bar m) and tetragonal phases (I4/m) were obtained using the VASP code. Tetragonal phases of all compounds of the form Cs2AgBiX6, except Cs2AgBiBr6, are reported here for the very first time. Among all the Cs2AgBiX6 (X = F, Cl, Br, I) structures, the cubic phase of Cs2AgBiBr6 was seen to have the highest absorption coefficient along with prominent electronic features that are favorable for optoelectronic applications. Thus, the cubic phase of Cs2AgBiBr6 was selected as the host lattice and bromine atoms were partly replaced with chlorine and iodine atoms. Electronic and optical properties of these mixed halide compounds of Cs2AgBiBr6-xFx, Cs2AgBiBr6-xClx, and Cs2AgBiBr6-xIx where x = 1, 2, 3, 4, 5 are investigated with hybrid functional HSE06 level. The electronic structure revealed that these mixed compounds exhibited indirect band gap nature regardless of the halide substitution (different x concentration) and the band gap of Cs2AgBiBr6 could be varied with the substitutions of fluorine, chlorine, and iodine atoms. Our in-depth analysis shows that Cs2AgBiBr6 and their mixed halides have the potential to become active double perovskite materials for photovoltaic applications and as photocatalysts for water splitting.

Materials made of indium oxide (In2O3) are now being used as a potential component of the next generation of computers and communication devices. Density functional theory is used to analyze the physical, electrical, and thermodynamical features of 12 low-energy bulk In2O3 polytypes. The cubic structure In2O3 is majorly used for many of the In2O3-based transparent conducting oxides. The objective of this study is to explore other new stable In2O3 polytypes that may exist. The structural properties and stability studies are performed using the Vienna ab initio simulation package code. All the In2O3 polytypes have semiconductive properties, according to electronic band structure investigations. The full elastic tensors and elastic moduli of all polytypes at 0 K are computed. Poisson's and Pugh's ratio confirms that all stable polytypes are ductile. The phonon and thermal properties including heat capacity are obtained for mechanically stable polytypes. For the first time, we report the Raman and infrared active modes of stable polytypes.

We investigate chalcogenide Ba2BiFeSe5 compound under pressure, focusing on temperature-dependent electrical resistivity ρ(T) upto 16.5 GPa and density functional theory (DFT) calculations up to 25 GPa. We assess Activation energies (Ea) and Bandgap calculations via the density of states (DOS). Our experimental results indicate a pressure-induced semiconductor-to-metal transition (STM) occurring at 14.3 GPa and transition is evident through the decreasing resistivity values from 14.7 × 105 Ω-cm to 0.00022 × 105 Ω-cm at 100 K and the calculated Ea, which decreases from 0.168 to 0.029 eV within 0–12 GPa range, followed by a sudden drop to 0.0007 eV at 14.3 GPa, signifying pressure-induced STM transition. Meanwhile, our DFT calculations reveal minor changes in the electronic band structure around 14 GPa. Furthermore, high-pressure DFT structural investigations affirm the stability of the Ba2BiFeSe5 system in a metallic state up to approximately 25 GPa. This unique phase transition holds significant promise for inspiring a diverse array of potential applications.

A fascinating transition-metal dichalcogenide (TMDC) compound, MoSe2, has attracted a lot of interest in electrochemical, photocatalytic, and optoelectronic systems. However, detailed studies on the structural stability of the various MoSe2 polymorphs are still lacking. For the first time, the relative stability of 11 different MoSe2 polymorphs (1H, 2H, 3Ha, 3Hb, 2T, 4T, 2R1, 1T1, 1T2, 3T, and 2R2) is proposed, and a detailed analysis of these polymorphs is carried out by employing the first-principles calculations based on density functional theory (DFT). We computed the physical properties of the polymorphs such as band structure, phonon, and elastic constants to examine the viability for real-world applications. The electronic properties of the involved polymorphs were calculated by employing the hybrid functional of Heyd, Scuseria, and Ernzerhof (HSE06). The energy band gap of the polymorphs (1H, 2H, 3Ha, 3Hb, 2T, 4T, and 2R1) is in the range of 1.6-1.8 eV, coinciding with the experimental value for the polymorph 2H. The covalent bonding nature of MoSe2 is analyzed from the charge density, charge transfer, and electron localization function. Among the 11 polymorphs, 1H, 2H, 2T, and 3Hb polymorphs are predicted as stable polymorphs based on the calculation of the mechanical and dynamical properties. Even though the 4T and 3Ha polymorphs' phonons are stable, they are mechanically unstable; hence, they are considered to be under a metastable condition. Additionally, we computed the direction-dependent elastic moduli and isotropic factors for both mechanically and dynamically stable polymorphs. Stable polymorphs are analyzed spectroscopically using IR and Raman spectra. The thermal stability of the polymorphs is also studied.

Green hydrogen produced from solar energy could be one of the solutions to the growing energy shortage as non-renewable energy sources are phased out. However, the current catalyst materials used for photocatalytic water splitting (PWS) cannot compete with other renewable technologies when it comes to efficiency and production cost. Transition-metal dichalcogenides, such as molybdenum disulfides (MoS2), have previously proven to have electronic and optical properties that could tackle these challenges. In this work, optical properties, the d-band center, and Gibbs free energy are calculated for seven MoS2 polymorphs using first-principles calculations and density functional theory (DFT) to show that they could be suitable as photocatalysts for PWS. Out of the seven, the two polymorphs 3Ha and 2R1 were shown to have d-band center values closest to the optimal value, while the Gibbs free energy for all seven polymorphs was within 5% of each other. In a previous study, we found that 3Hb had the highest electron mobility among all seven polymorphs and an optimal bandgap for photocatalytic reactions. The 3Hb polymorphs were therefore selected for further study. An in-depth analysis of the enhancement of the electronic properties and the Gibbs free energy through substitutional doping with Al, Co, N, and Ni was carried out. For the very first time, substitutional doping of MoS2 was attempted. We found that replacing one Mo atom with Al, Co, I, N, and Ni lowered the Gibbs free energy by a factor of 10, which would increase the hydrogen evolution reaction of the catalyst. Our study further shows that 3Hb with one S atom replaced with Al, Co, I, N, or Ni is dynamically and mechanically stable, while for 3Hb, replacing one Mo atom with Al and Ni makes the structure stable. Based on the low Gibbs free energy, stability, and electronic bandgap 3Hb, MoS2 doped with Al for one Mo atom emerges as a promising candidate for photocatalytic water splitting.

Rhombic dodecahedron-architecturedNi-Cu nanostructurespinned with N-doped carbon (Ni-Cu/NC) are manufactured usingNi-Cu-zeolitic imidazolate frameworks (Ni-Cu-ZIF-8)as soft templates. The as-established ZIF-8 and metal/NC series nanocatalystsare loaded on biodegradable butter sheet papers (BSPs) and used asflexible electrochemical probes for high-performance electrochemicalnonenzymatic glucose sensors (ENEGSs). The optimized molecular andelectronic structures and charge density distribution of as-formulatedZIF-8 and metal/C series nanostructures are realized with DFT studies,and the influences of aforesaid unique properties on glucose electrooxidationare established with various electrochemical techniques. Owing tothe robust carbon network-interlaced metallic units, high electricalconductivity, large surface area, and extended active sites, Ni-Cu-ZIF-8-derivedNi-Cu/NC demonstrates the elevated ENEGS performance includinglower detection limit, high sensitivity, and elevated specificityunder alkaline regimes that actualize Ni-Cu/NC/BSP'spractical glucose sensingrecognition in human serum. Thus, the as-fabricated Ni-Cu/NC/BSPextends exclusive benefits of having simple fabrication and beingcost-efficient, reliable, and reusable, along with high glucose sensingperformance, accessing innovative conveniences to epitomize technicallysound and economically viable boulevards in the amplification of ENEGSs.