Although tin oxide catalysts have been extensively used in electrocatalytic CO2 reduction (CO2ER) to HCOOH (including both HCOO- and HCOOH), the identification of the active site and the underlying reaction mechanism remain subjects of debate. Through constant-potential density functional theory (DFT) calculations and microkinetic simulations, we have pinpointed the Sn-5 site on SnO2(110) surfaces as the active site, where CO2ER proceeds via a CO2_n (binding through O atoms)-mediated mechanism, noticeably distinct from the mechanisms identified via the constant-charge method. The significant stabilization of CO2_n species at the Sn-5 site can be explained by the hard and soft acids and bases (HSAB) principle. Furthermore, the synergetic interaction between Sn-5 and Sn-4 sites offers an additional pathway for the formation of adsorbed hydrogen species at potentials more negative than -1.2 V, thereby enhancing the current density and Faradaic efficiency of HCOOH on SnO2(110). The simulated Faradaic efficiencies and current densities of products align well with experimental observations on tin oxide catalysts. This study highlights the essential role of the constant-potential method in elucidating the active site and CO2ER mechanism on SnO2(110), providing insights that can enrich the design principles for CO2ER and other technologically relevant reactions.

Although Pd catalysts modified with Au have been widely used in formic acid (HCOOH) decomposition for hydrogen storage, the active site and reaction mechanism remain under debate. We developed a computational method for simulating temperature-programmed surface reaction (TPSR) experiments that not only captures product desorption features but also tracks the concentration changes of intermediates as a function of temperature. This capability provides mechanistic insights into key intermediates and their associated reaction pathways toward product formation, which are difficult to obtain using conventional surface science techniques. We used this method to simulate TPSR spectra for HCOOH decomposition on Pd(111) and possible PdAu active configurations, including core-shell and surface alloy configurations. The simulated spectra for Pd(111) and Pd2Au/Au(111) surface alloy agree well with the TPSR experiments on Pd(111) and PdAu catalysts, which validates the reliability of our method and suggests that the active sites of the PdAu catalyst resemble PdPdAu sites in the Pd2Au/Au(111) surface alloy. The HCOOH decomposition pathway shifts from the formate pathway on Pd(111) to the carboxyl pathway on Pd2Au/Au(111), which is attributed to the smaller Pd ensemble sites required for the latter. This work enriches the design principles for HCOOH decomposition catalysts and demonstrates the potential of the TPSR simulation method in elucidating catalytic reaction mechanisms.

This study developed a selective phosphorization strategy to precisely construct distorted asymmetric FeP3C1-coordinated Fe single-atom catalysts (SACs) on graphitic carbon nitride (g-C3N4) to overcome the poor charge separation and unbalanced reaction intermediate adsorption arising from the highly symmetric coordination structures of SACs. Moreover, tunable modulation of the local dipole moments and charge distributions was achieved at the Fe sites by finely adjusting the phosphorization time to control the phosphorus doping level. Integrated experimental characterization and density functional theory calculations revealed that the distorted asymmetric FeP3C1 configuration significantly enhanced interfacial dipole moments, accelerating photogenerated charge separation while broadening visible-light absorption. Furthermore, the dipole-induced asymmetric charge distribution optimized the adsorption behavior of hydrogen intermediates; this lowered the Gibbs free energy barrier for the hydrogen evolution reaction (HER), leading to the the thermodynamic optimum. The resulting FeP3C1/g-C3N4 displayed outstanding performance even without noble-metal co-catalysts, achieving an HER rate of 7045 ± 195 μmol g-1 h-1 and a peak apparent quantum efficiency of 12.87% at 380 nm. Thus, this work establishes distortion-driven asymmetric coordination engineering and the associated dipole moment enhancement as a new paradigm for efficient solar-to‑hydrogen conversion catalysts designs.

To address the limitations of inefficient charge separation and imbalanced reaction intermediate adsorption that are inherent to the highly symmetric coordination structures of single-atom catalysts (SACs), a selective phosphorization strategy was developed for the precise construction of distorted asymmetric FeP3C1-coordinated Fe SACs on graphitic carbon nitride (g-C3N4). Through careful control of the phosphorization duration to regulate the phosphorus doping levels, tailored modulation was achieved for both the local dipole moments and the charge distributions at the Fe sites. Integrated experimental characterization and density functional theory calculations demonstrated that the distorted asymmetric FeP3C1 configuration significantly enhanced interfacial dipole moments, accelerating photogenerated charge separation while broadening the visible-light absorption. More importantly, the dipole-induced asymmetric charge distribution optimized the adsorption behavior of hydrogen intermediates, thereby lowering the Gibbs free energy barrier for the hydrogen evolution reaction (HER) and driving it toward the thermodynamic optimum. The FeP3C1/g-C3N4 exhibited an exceptional performance in the absence of noble-metal co-catalysts, achieving an HER rate of 7044.72 μmol g-1 h-1 and a peak apparent quantum efficiency of 12.87% at 380 nm. This work therefore establishes distortion-driven asymmetric coordination engineering and the associated dipole moment enhancement as a new paradigm for the design of efficient solar-to-hydrogen conversion catalysts.

Formic acid (HCOOH) has emerged as a promising liquid-phase hydrogen carrier, releasing hydrogen under mild conditions via catalytic decomposition. While Pd is widely studied for this reaction, its practical performance requires significant improvement. We utilize Br & oslash;nsted-Evans-Polanyi (BEP) relation predicted activation energies and microkinetic modeling to screen a number of PdMPd (M = Group VIII and IB transition metals) subsurface alloy catalysts, and identify PdRuPd(111) and PdNiPd(111) as promising candidates. Density functional theory calculated activation energies and microkinetic analysis confirm their superior activity-surpassing Pd(111) by 3-4 orders of magnitude at 400 K and 1 bar-while maintaining H2 selectivity higher than 99.99 %. HCOOH decomposition on the two surfaces proceeds through HCOO* dehydrogenation mechanism, with the ratedetermining steps being HCOO* dehydrogenation and CO* desorption, which is distinct from COOH* dehydrogenation mechanism on Pd(111). The computational screening based on BEP relation and microkinetic modeling offers an efficient tool for accelerated catalyst discovery, which can be potentially applied to other important reactions of technological interest.

Zinc cadmium sulfide (ZCS) is a promising photocatalyst owing to its tunable bandgap and strong visible light absorption ability. However, the rapid recombination of photogenerated charge carriers and severe photocorrosion hinder its application. To address these challenges, a conceptually new form of phosphorus-dominated redox sites on ZCS was synthesized via a one-step photochemical modification method. Experiments and density functional theory calculations revealed that the intrinsic piezoelectric field of ZCS optimized the dynamic separation of the photogenerated carriers, and simultaneously the POx layer enhanced the photocorrosion resistance of ZCS. Moreover, the FeNiP sites promoted water adsorption and H2 evolution, while the phosphorus vacancy (Pvac) sites of POx facilitated H2O2 evolution. The synergistic effect of these redox sites lowered the free-energy barriers for H2 and H2O2 evolution to 0.19 and 1.87 eV, respectively. As a result, the prepared FeNiP/ZCS/POx catalyst achieved an apparent quantum efficiency of 7.32% at 420 nm. Piezo-photocatalytic water splitting yielded H2 and H2O2 at the rates of 2.556 and 2.075 mmol & sdot;h- 1 & sdot;g- 1, respectively, with the H2/H2O2 molar ratio of approximately 1:1. Moreover, the optimized FeNiP/ZCS/POx catalyst maintained excellent stability over 60 h. This study provides a strategy for designing highly efficient ZCS-based photocatalysts for pure water splitting.

Manipulating oriented electron flow and tailored reaction microenvironments in radial-unguided two-dimensional phosphorene remains challenging. Here, we show that Rh-decorated violet/black phosphorus heterostructures, engineered with integrative dual-electric fields from cooperative phase and fringing electric field, enable efficient vapor-fed photocatalytic hydrogen production. This dual-electric field establishes a strong intrinsic charge driving force and edge charge ordering. The vapor-fed gas-solid system minimizes interfacial diffusion barriers and solvent shielding, allowing the field to steer photoelectrons and interact with H2O molecules at the edge-located Rh active centers. Analyses reveal that the integrative dual-electric field strengthens polarization and overcomes the water dissociation barrier at the gas-solid interface. The optimized catalyst achieves a H2-generation rate of 5218.7 μmol g-1 h-1 under simulated sunlight, roughly 2.4 times conventional liquid-solid systems. This work demonstrates that synergy between integrative dual-electric fields and the gas-solid microenvironment overcome the kinetic limitations of phosphorene-based photocatalysts for efficient solar-driven hydrogen conversion.

Catalytic activities have been found to correlate with the adsorption energies of key intermediates in many catalytic reactions, and computational screening based on the adsorption energies of such intermediates has been widely used for catalyst discovery. High-entropy alloys (HEAs) offer an expansive configuration space, leading to a near-continuous distribution of adsorption energies for intermediates, thereby facilitating the identification of promising catalysts with optimal adsorption energies. However, comprehensive DFT calculations of adsorption energies on HEAs are hindered by the vast number of surface arrangements. Using the SISSO approach and DFT calculations, the adsorption energies of CO on the HEA AuCuIrPdPt(111) surfaces are predicted to identify improved catalysts for HCOOH decomposition, which provides a potential solution to hydrogen storage. We identify Au8Cu5IrPd21Pt13, Pd2Au2 and Pd2Au/Pd as promising candidates, and DFT calculations and microkinetic modeling show that the systems present superior activity to conventional Pd catalysts by three orders of magnitude at 400 K while maintaining high H2 selectivity. HCOOH decomposition proceeds through HCOO* and COOH* species on Au8Cu5IrPd21Pt13, Pd2Au2 and Pd2Au/Pd, with the rate-determining steps being HCOO* and COOH* dehydrogenation, respectively. Various PdAu surface alloys with varied Pd/Au ratios also exhibit salient activities, which agrees well with the superior performance of PdAu catalysts widely observed in experimental studies. This work highlights the importance of the ensemble effect in HCOOH decomposition, and the combination of a data-driven approach, DFT calculations and microkinetic modeling provides a powerful tool for fast catalyst discovery.

Single-atom catalysts (SACs) display prominent performance and high metal utilization for numerous catalytic processes. Harnessing the interaction between single atoms and supports is crucial to improve the performance of SACs. By means of density functional theory calculations and microkinetic modeling including adsorbate interactions, we expose the promising synergy between 3d-5d single metal atoms (M) and TiO2(110) for CO oxidation. Upon a rigorous analysis, we identify the adsorption energy of O at M sites as a simple and robust descriptor to abridge the design of catalysts for CO oxidation on M/TiO2 catalysts, so that enhanced activities are predicted at mild O adsorption energies. Single Pt and Rh atoms provide the largest enhancement around 400 K, with CO2 formation rates 7-8 orders of magnitude higher than on TiO2(110). Non-precious Ta/TiO2 and Mn/ TiO2 also exhibit salient activities. This work highlights the often disregarded yet central role of adsorbate interactions in CO oxidation.

The CO2 electrochemical reduction (CO2ER) to formic acid offers a potential solution to a carbon-neutral energy cycle. However, this process is mainly limited by sluggish kinetics and low selectivity for HCOOH/HCOO- over H-2 on Sn-based catalysts. Despite extensive research, the exact reaction mechanism remains contentious. Using constant-potential first-principles study and microkinetic modeling, we identify a reaction pathway involving bent CO(2_)v* intermediate on Sn(200), which is clearly distinct from previous studies by the constant-charge approach. Following this pathway, the simulated CO2ER/hydrogen evolution reaction polarization curves, as well as Faradaic efficiency on Sn(200), exhibit good agreement with experimental findings. The potential-dependent selectivity switch from HCOOH/HCOO- to H-2 is attributed to the changing stability of CO2_v* with applied potential. Both excessively stable and overly unstable CO2_v* intermediates are detrimental to HCOOH formation. Moreover, we find that enhancing the adsorption of HCOO* can boost the current density and selectivity for HCOOH/HCOO- production on Sn(200). This work highlights the importance of precisely describing the electrochemical interface by the constant-potential approach in elucidating the CO2ER mechanism, and the insights gained can potentially be used to develop improved electrocatalysts for the CO2ER and other important reactions of technological interest.

CO conversion rate follows the order S edge > Mo edge > Cu/MoS 2 (001). Redox and associative routes are dominant on Cu/MoS 2 (001) and S edge, respectively, while both routes contribute to water-gas shift on Mo edge.

Ammonia decomposition provides a potential route for the production of COx-free hydrogen. Despite numerous studies, the active sites and reaction mechanism remain in debate. To date, only N-N recombination mechanism, in which N-2* is formed by the N* atoms recombination, is investigated on the archetypical Ru catalyst and Ru B-5 site has been identified as the active site. Combined density functional theory calculation and microkinetic modeling, we show that the N2Hy* (y > 0) dehydrogenation mechanism, which involves the stepwise N2Hy* dehydrogenation to N-2*, is important and even dominant on Ru defect sites at low temperatures, elevated PNH3 or P-H2 where the coverage of vacant sites is low so that the NHx (x = 1-3) dehydrogenation is suppressed. Regardless of reaction conditions, Ru A(4) and kink sites show higher activity than the conventional B-5 site, with the rate-determining steps of NH3 adsorption and H-2 desorption. Inhibition of the ammonia decomposition rate by the hydrogen produced originates from the low dissociation barrier of hydrogen. This work reveals the interplay between surface structure, reaction condition and mechanism for ammonia decomposition on Ru catalyst, and the insights can enrich the design principles of catalysts for the ammonia decomposition and other important reactions of technological interest.

In response to the reform and innovation of higher education in the post-COVID era and based on the online teaching resources built during the pandemic, a student-centered online teaching new mode was actively explored in Coatings Technology. Through the teaching cloud platform and online teaching activities, teachers guided students to learn actively, and explained the difficulties and key points of the course, which was combined with Tencent classroom live broadcast and supplemented by Wechat or QQ course group for real-time communication and Q ＆ A.Teaching practice showed that student’s consciousness of active learning had been strengthened through online teaching new mode, and the autonomous learning and cooperative learning were promoted. The student’s innovative thinking had been cultivated. Therefore, the exploration had a certain value of application.

The enrichment of tetracycline (TC) in the environment will harm human and animal tissues and lead to bacterial resistance. The MIL or ZIF derived magnetic carbon adsorbents have great potential for the removal of TC, whereas its low concentration of metals limits the adsorption efficiency. By one-step annealing Co-hexamine coordination frameworks at 700 degrees C, the ultrahigh Co concentration (86.10 wt%) and abundant doped nitrogen (2.85 at%) are achieved in the nitrogen-doped carbons encapsulated cobalt nanoparticles (Co@NC-700). The optimized Co@NC-700 composite exhibits a supercolossal TC adsorption capacity of 3496.54 mg g(-1), which is similar to 6 times that of the traditional adsorbents, and the removal capacity maintains at 94.22% after four cycles. The adsorption of TC follows Pseudo-second-order and Elovich kinetic models, suggesting a chemisorption process. The adsorption isotherm had good compatibility with Freundlich model, confirming the crucial role of multi-layer adsorption on the high adsorption capacity. Experiments and characterizations revealed the dominant effect of pi-pi electron donor-acceptor (EDA) interaction and surface complexation on the adsorption of TC. Density functional theory calculations demonstrate that the encapsulated cobalt formed complex bond with TC through the pore and pyridinic-N enhance the pi-pi EDA interaction. This work demonstrates a strategy of preparing magnetic carbon material with ultrahigh metal concentration, which opens up a new avenue for highly efficient adsorbent development in the removal of antibiotics and pollutants.

The electroreduction of CO to C2 products (primarily C2H4 and EtOH) provides a promising route to both carbon neutrality and energy storage and conversion under mild conditions. However, the commonly used copper catalyst suffers from high overpotentials, which has been shown to be closely related to CO dimerization reac-tion. Using density functional theory calculations, we study the effect of composition and structure of CuM(1 0 0) surface (M = Ru, Au, Zn and Ga) and Cu/M(1 0 0) subsurface (M = 3d Sc-Zn) alloys on the relative stability of 2CO and C2O2. We show that the higher stability of C2O2 relative to 2CO and enhanced CO electroreduction activity are achieved through increasing the interlayer separation of Cu (100) by the presence of subsurface Sc and Ti, which decrease the overlap between the dz2 orbitals of surface Cu and subsurface atoms and destabilizes the sigma bond of Cu-CO more than that of Cu-C2O2. This modification also largely facilitates the C2H4 formation instead of EtOH formation through a substantial stabilization of the adsorbed intermediates. This work opens up an avenue for the design and development of catalyst in CO/CO2 electroreduction and other important reactions of technological interest.

The ammonia synthesis by Haber-Bosch process is an important catalytic process for the production of fertilizers. Despite extensive research, the exact reaction mechanism remains unsettled. To date, only dissociative mecha-nism, in which the adsorbed N2 decomposes directly, is investigated on the archetypical Ru-based catalyst. By density functional theory calculation and micro-kinetic modeling, we show that the associative mechanism, which is initiated by N2 hydrogenation to NNH, is dominant on Ru terrace, vacancy and adatom sites regardless of temperatures (523.15-723.15 K) and sticking coefficients (or partial pressures) of N2 and H2 (SN2 = 1.0 x 10-12-1.0 and SH2 = 0.001-1.0). The associative mechanism also dominates on Ru step (A4) and kink sites at a high SN2 or SH2 (SN2 = 1.0 or SH2 = 1.0), which exhibit higher reaction rate than Ru B5 site. The preferable associative mechanism originates from the high theta H*/theta* ratio or the significant backward process of N2* disso-ciation induced by high theta N*/theta* ratio, and has markedly different rate-determining step from the traditional dissociative mechanism (N2 hydrogenation vs dissociation). We also show that the equilibrium approximation is more convenient and efficient than the micro-kinetic modeling, which can streamline the fundamental under-standing and accelerate the high-throughput screening of ammonia synthesis materials.

Molybdenum disulphide (MoS2) has attracted much attention as a promising non-precious metal catalyst for CO2 hydrogenation to energy-rich commodities. However, the exact reaction mechanism and active site on the MoS2 catalyst are still a matter of debate. Using density functional theory (DFT) calculations and microkinetic modeling, we study the competitive pathways leading to the formation of CO, methane and methanol at the S edge site in MoS2 catalyst, and the results are compared to those on the Mo edge and MoS2(001) in our previous work. It is found that CO is exclusively produced through redox mechanism on the S edge at 580-780 K, 1bar and H2/CO2 ratio of 1, with the rate determining step of C-O bond scission in CO2. The rate of CO formation follows the order of Mo edge > S edge > MoS2(001), suggesting the Mo edge as the likely active site on the MoS2 catalyst. This work offers a mechanistic understanding toward CO2 hydrogenation on the MoS2 catalyst at the atomic level, and the insights gained can be used to design improved catalysts for the CO2 and CO hydrogenation and other important reactions of technological interest.

Capping agents such as halide and citrate (CA) are crucial in the colloidal synthesis of noble metal nanoparticles (NPs) with desirable shape for specific catalytic reaction. Halide ions have been shown to stabilize the cubic NP while CA ions favor the octahedral NP regardless of the noble metals, but the mechanism remains unclear. We combine DFT calculations and Wulff construction to understand how the morphology of Pd particle changes with Cl and CA chemical potential (& mu;). Three main factors are identified to affect the morphology of Pd particle: & mu; of adsorbate, its number per unit area (NAS/S), and rigidity or flexibility. Increasing & mu; of adsorbate or its NAS/S causes decreased surface free energy and increased exposed surface area. Moreover, rigid adsorbates (PdClx) occupy a larger surface area for surfaces with high atomic density such as Pd(1 1 1), leading to cubic Pd particle at high & mu;Cl. Conversely, flexible adsorbates (CA) that can adjust their structure based on the surface occupy smaller surface area on Pd(1 1 1), favoring octahedral Pd particle. This work reveals the origin for capping agent tuned morphology of Pd NP, and the insights can be used to guide metal NP synthesis with desired morphology for catalytic reactions of technological interest.

MoS2 catalysts hold great promise for numerous reactions of industrial and technological interest. However, general guidelines for the design of their active sites remain elusive. We hypothesize that this is because the link between their geometric structure and reactivity is yet to be established at the atomic scale. Here we show that cn, a metric based on the number of sulfur atoms coordinated to Mo atoms, captures the trends in reactivity of MoS2 catalysts with various sulfur vacancy contents. This is illustrated for the adsorption energies of numerous monatomic and polyatomic species. More importantly, cn can be used to predict the reaction and activation energies of common formation and dissociation reactions in catalysis. Finally, cn is used to outline the optimal configuration of MoS2 active sites for the electrocatalytic hydrogen evolution reaction: the highest exchange current density corresponds to terrace sites with adjacent S vacancies with cn in the range of 4.33 to 4.67.