Visible-light-driven one-step excitation photocatalytic overall water splitting (OWS) under ambient pressure constitutes a sustainable route for the conversion of inexhaustible solar energy into clean hydrogen energy. Although graphitic carbon nitride (C3N4) possesses both visible-light responsiveness and a moderate band structure, its catalytic efficiency is drastically hampered by the rapid recombination of photoexcited carriers and inevitable hydrogen-oxygen reverse reactions. To overcome these critical bottlenecks, a Cr2O3/Pt/C3N4 catalyst was successfully constructed via in situ photodeposition. Notably, the as-prepared Cr2O3/Pt/C3N4 catalyst enables efficient visible-light-driven one-step excitation OWS, exhibiting a catalytic activity 4 times superior to that of pristine Pt/C3N4. Combining density functional theory (DFT) calculations and structural characterization, it was found that the in situ deposited Cr2O3 protective layer on the cocatalyst effectively modulates the electronic structure and adsorption energy of Pt, thereby inhibiting the oxygen-hydrogen recombination reaction and enabling stable and efficient hydrogen production. This work thereby lays a theoretical foundation and offers technical pathways for the design strategy and application exploration of highly efficient C3N4-based photocatalysts.

The development of cost-effective and facile-to-fabricate non-precious metal-based bifunctional electrocatalysts represents a critical challenge for achieving green hydrogen production via water electrolysis. To address this, this study employs waste agricultural biomass, specifically grapefruit peel, as a green and renewable carbon precursor. Through a simple and scalable impregnation-pyrolysis strategy, we successfully constructed a graphitic carbon-supported, N/Fe-codoped NiCo-based core-shell bifunctional electrocatalyst. The optimal catalyst demonstrates exceptional performance, requiring overpotentials as low as 124 mV for the hydrogen evolution reaction (HER) at 10 mA cm-2 and 290 mV for the oxygen evolution reaction (OER) at 50 mA cm-2. This work provides a universal design strategy for constructing highly active, low-cost non-precious metal bifunctional electrocatalysts from waste biomass, offering valuable insights for advancing the scalable and sustainable development of water electrolysis technology.

Amidst escalating global energy crises and environmental degradation, biomass resources offer a critical pathway for energy transition through their inherent renewability, carbon neutrality, and abundance. However, efficient conversion of waste biomass remains impeded by compositional complexity and suboptimal process energetics, constraining scalable industrial implementation. Building on this, we innovatively utilize waste grapefruit peel as a multifunctional precursor to construct Ni-Mo₂C heterojunction nanocomposites (Ni-Mo₂C/NGC) on a biomass-derived N-doped graphene-like carbon matrix (NGC) via an in situ one-step pyrolysis strategy. Electrocatalytic evaluation reveals that the nanocomposite exhibits outstanding bifunctional activity for both oxygen and hydrogen evolution reactions (OER/HER) in alkaline electrolyte, achieving low overpotentials (η) of 260 mV for OER and 120 mV for HER at a current density of 10 mA cm⁻², with corresponding Tafel slopes of 48 and 52 mV dec⁻¹, respectively. Density functional theory (DFT) calculations elucidate that synergistic interfacial electron coupling between Ni and Mo₂C at the heterojunction significantly elevates the density of exposed catalytic active sites, optimizes the adsorption free energy of key reaction intermediates, and accelerates interfacial charge transfer kinetics, thereby cooperatively enhancing the intrinsic bifunctional electrocatalytic activity. This study establishes a novel strategy for the high-value-oriented preparation of high-performance electrocatalysts from waste biomass, providing insights into the construction of non-precious metal bifunctional heterojunction catalysts.

Creating more interfaces within metal selenides-based materials to leverage the vast potential of composites in sodium-ion batteries (SIBs) is highly desirable. However, it remains challenging due to differences in compatibility among various components and the complexity of synthesis methods. In this work, three-phase metal selenide heterostructures embedded porous carbon composites (Cu2-xSe/MnSe/ZnSe@C) are prepared through one-step pyrolysis of ternary metal-organic framework precursors. Density functional theory calculations and various characterizations reveal that the three-phase Cu2-xSe/MnSe/ZnSe heterostructure shows higher electrical conductivity, faster electron transport, and lower Na+ diffusion energy barrier compared to Cu2-xSe/MnSe and Cu2-xSe/ZnSe. When evaluated as an anode for SIBs, its unique structure and component advantages endow the optimized material with superior electrochemical performance, including high capacities (454.8 mAh g-1 at 0.1 A g-1), excellent rate capability with the capacity retention rate of 88.0 % at 10.0 A g-1 (369.2 mAh g-1) compared to that at 0.1 A g-1, and long-term cycling stability at high densities. Furthermore, cyclic voltammetry and ex-situ X-ray diffraction patterns verify the combined insertion and conversion reaction mechanisms.

Carbon nitride-based heterojunction catalysts show broad application prospects for the degradation of wastewater pollutants (e.g. antibiotics and dyes), yet their performance remains challenges in narrow light absorption range and high carrier recombination rate. The introduction of components with matched band structures and surface plasmon resonance can mitigate these limitations. Herein, a Schottky heterojunction composed of plasma Bi and MoO2-incorporated carbon nitride (Bi/MoO2@CN) is designed and synthesized via solvothermalcalcination method. Multiple preparation parameters are optimized to achieve the reduction of Bi2MoO6 (BMO) to plasma Bi metal and MoO2. The synergistic structural and compositional effects endow the optimal material with exceptional adsorption-photocatalytic activity, achieving 96.19% tetracycline (TC) degradation within 90 min under visible light. The first-order kinetic constant is seven times higher than CN. The catalyst also demonstrates versatility in removing diverse organic dyes. Active species trapping experiments identify holes (h+) and superoxide radicals (center dot O-2 ) as primary reactive species. Furthermore, enhanced photocatalytic mechanism is elucidated through band structure analysis, Schottky heterojunction characterization, and TC degradation pathway study.

To address the remediation needs of antibiotic-contaminated water, this study developed a highly efficient and stable novel photocatalyst. A 2D/3D S-scheme g-C3N4/Bi2MoO6 (CN/BMO) heterojunction was synthesized via a simple preparation method, with its core mechanism relying on the internal electric field (IEF) formed at the semiconductor interface. This field actively regulates the S-scheme charge transfer pathway, a process directly validated through a series of photoelectrochemical analyses: significantly quenched photoluminescence signals and shortened carrier lifetimes confirmed efficient interfacial recombination, while enhanced photocurrent responses and reduced electrochemical impedance indicated effective spatial separation of electron-hole pairs. The optimized carrier separation efficiency significantly improved the photocatalytic performance of the material. Under visible light irradiation, the degradation efficiency of tetracycline (TC) reached 85%, with degradation rates exceeding 80% for multiple antibiotic pollutants. Additionally, the material exhibited excellent stability in five consecutive cycling experiments. Mechanistic studies revealed that the synergistic effect of superoxide radicals (& sdot;O-2 ) and photogenerated holes (h+) dominated the reaction process, as conclusively verified by electron paramagnetic resonance (EPR) spectroscopy. Degradation pathway analysis via mass spectrometry (MC-LS) demonstrated that TC primarily undergoes cleavage through demethylation, hydroxylation, and ring-opening reactions, with simultaneous assessment of the toxicity and ecological risks of reaction intermediates. This work provides new theoretical foundations and practical solutions for the photocatalytic removal of antibiotics in real water bodies.

Searching for low cost, high activity, and stable oxygen evolution reaction (OER) electrocatalysts based on earth-abundant Fe, Co, and Ni metals is highly desirable for sustainable hydrogen production. Herein, a novel aggregated nanoparticle-cluster structured FeCoNiGaMo high-entropy oxide composite was fabricated via a facile solution combustion synthesis followed by a post-annealing crystallization process. Structural characterizations show that the architecture can significantly increase the electrochemical active surface area, fully exposing the abundant catalytically active sites. Benefiting from optimized annealing temperature, annealing duration, and glucose-to-urea ratio, the as-obtained catalyst delivers a low overpotential of only 280mV at 10mAcm-2. Furthermore, it demonstrates exceptional long-term durability, operating for over 130hours at 250mAcm-2 with minimal overpotential attenuation and maintaining its structural integrity even after prolonged cycling tests. Systematic characterizations reveal that Mo incorporation serves as the intrinsic driving force for the spontaneous spinel/molybdate phase separation, owing to the coordination incompatibility between Mo6+ and transition-metal cations. This work offers a fresh perspective on the rational design of high-entropy oxide electrocatalysts through phase separation and modulation of heterostructures.

Self-supported nonprecious metal selenide electrocatalysts have demonstrated significant potential for oxygen evolution reaction, due to stable spatial framework and extensive electrochemical interface. However, the design and construction of metal selenides, particularly heterostructures, continue to pose significant challenges. In this work, self-supported Ni-Co selenide heterostructures were successfully fabricated via a one-step selenization process utilizing the hydroxide precursor. The electrocatalytic performance of the composite was systematically examined, focusing on the influence of selenization temperature and the Ni/Co molar ratio. As expected, the optimal composite shows remarkable electrocatalytic performance in an alkaline environment, achieving an overpotential of merely 291 mV at 50 mA cm-2, surpassing numerous previously reported Co- and Ni-based electrocatalysts. Additionally, the electrocatalyst demonstrates exceptional cyclability and maintains its structural and compositional integrity even after stability testing.

Covalent triazine frameworks (C0054Fs) are promising electrode materials due to their rigid bonds, high surface area, and porosity, addressing the challenges of poor stability and slow electron diffusion in traditional materials, therefore, this experiment proposes that CTF-2 prepared by 4,4-biphenyl dicarbonitrile is used for rechargeable zinc-air battery electrocatalytic materials. Notably, the electrochemical properties were improved by incorporating bimetallic oxides into the CTF-2 precursor, where each triazine ring and bimetallic oxide provided empty orbitals that could deliver electrons, which enhanced the electron transfer between the triazine ring and the metal ions, with the number of electrons transferred found to be close to 4 electrons by testing, and the half-wave potential of ORR in the electrolyte for the catalysts prepared in the present experiments (CoFe2O4@CN/CTF-2) is The half-wave potential of ORR in the electrolyte was 0.84 V similar to that of Pt/C, whereas the overpotential of OER was 330 mV, superior to that of Pt/C by 10 mA at a current density of 10 mA cm-2, thus demonstrating that the bifunctional electrocatalytic activity of the ORR/OER of CoFe2O4@CN/CTF-2 was obviously enhanced.

As a well-established photocatalyst responsive to visible light, C3N4 exhibits substantial potential in the field of overall water splitting. However, efficiency and stability are the two key points for C3N4 photocatalysts because their application has been seriously restricted due to a serious photocorrosion issue and the recombination of photogenerated charge pairs. In this work, dual active-site cocatalysts comprising Pt@Cr2O3 and MnOx were precisely constructed on the surface of C3N4. The resulting Cr2O3/Pt/C3N4/MnOx composite photocatalyst exhibited remarkably enhanced photocatalytic stability. The H-2 evolution rate of the composite reached 4.38 mu molh(-1), which is approximately 56 times higher than that of Pt/C3N4 (0.078 mu molh(-1)). Detailed mechanistic studies reveal that the introduction of MnOx onto Pt/C3N4 facilitates charge carrier transfer, promotes the timely decomposition of newly formed peroxides, and significantly improves the corrosion resistance of C3N4. Meanwhile, the presence of Cr2O3 effectively suppresses the reverse reaction between hydrogen and oxygen, thereby further enhancing the overall water-splitting efficiency. This work provides novel insights for the design and development of highly efficient and stable C3N4-based photocatalysts for sustainable solar-driven water splitting.

Hierarchical TiO2/NC composites with large specific surface areas and excellent light use efficiency were prepared by self-assembly technique without any additional agents. Depending on the functional groups on the surface of the graphene like NC nanosheets, TiO2 nanoparticles with the size of about 4 nm stacked each other and anchored homogeneously on the surface of the graphene like NC nanosheets forming nanosheets with the thickness of 20-35 nm. These nanosheets crossed each other forming flower like hierarchical structure which is beneficial to the utilization of light. Moreover, the specific surface area of TiO2/NC composites were improved to 4.5 times of NC material due to existence of TiO2 nanoparticles with tiny size and the exfoliation of the graphene like NC nanosheets. Owing to the strong interaction between TiO2 nanoparticles and the graphene like NC nanosheets, carbon and nitrogen doped into the crystal lattice of TiO2 nanoparticles making the light scope of TiO2 expanded obviously. In the effect of multiple influencing factors of good conductivity of the graphene like NC material, wide light absorption range and the special hierarchical structure, the number of photoelectrons and holes increased and transferred to surface of TiO2/NC composites quickly. Test data revealed that the reaction rate constant of the TiO2@NC-2 composites material reached 4.12 x 10-4 mg- 1 center dot L center dot min- 1, representing a 1.8-fold increase over pure TiO2, demonstrating excellent photocatalytic performance. This can be attributed to, these photoelectrons reacted with oxygen adsorbed on the graphene like NC nanosheets to produce abundant superoxide radical with strong oxidizing ability, making the photocatalytic performance of TiO2/NC composites under visible light enhanced.

In this work, two series of plasmonic S-type heterojunction photocatalysts containing Bi, TiO2, and biochar (Bi/ TiO2@C) have been developed through a biomass-assisted hydrothermal-calcination strategy, utilizing grapefruit peel as a reducing agent and C resource. The calcination temperature and the mass ratio of biomass were optimized to obtain the optimal nanocomposite, which shows excellent adsorptive and visible-light photo- catalytic performance in the removal of diverse antibiotic and dye pollutants, including tetracycline, oxytetracycline, ciprofloxacin, sulfamethoxazole, sulfisoxazole, malachite green, and rhodamine B. The remarkable performance can be attributed to the enhanced absorption of light absorption resulting from the localized surface plasmon resonance effect of the semimetal Bi, and the formation of heterogeneous interface between Bi and TiO2, which accelerates the transfer of photogenerated charge. Furthermore, trapping tests and electron spin resonance (ESR) analysis reveal that center dot O2- and h+ are the primary active species involved in the removal of tetracycline. A plausible charge transfer mechanism has been proposed.

The design and construction of low-cost, efficient, and robust oxygen evolution electrocatalysts is critical for sustainable energy conversion. In this work, a simple impregnation-pyrolysis approach is developed to synthesize nitrogen, oxygen-codoped biochar-encapsulated quaternary FeCoNiCu alloy catalyst. Here, waste biomass serves as both a carbon template and a reducing agent, facilitating the formation of biochar and ensuring the transformation of alloys as well as their uniform dispersion. When evaluated as the electrocatalyst in the oxygen evolution reaction, the sample obtained at optimized pyrolysis temperature and biomass amount exhibits a low overpotential of only 300 mV at 10 mA cm-2, remarkable stability with the current density of 20 mA cm-2 remaining virtually unchanged even after of 60 h, and good structural preservation after long-term cycling. Density functional theory calculation shows that the formation of Cu-Co bonds is crucial is crucial for achieving high electrocatalytic activity of the catalyst.

Here, two Ni/NiO@C hollow-fiber composites were created, exhibiting magnetic, adsorbent, and electrocatalytic (OER/HER) properties. Our approach was a straightforward, eco-friendly, two-step dipping/adsorbing-calcining method, using Ni(NO3)26H2O and biomass cotton fiber (CF) as starting materials. We then thoroughly characterized the resulting materials using a suite of techniques, including SEM, TEM, XRD, BET, and XPS, to get a good handle on their properties. The morphology, composition, and properties of synthesized materials were analyzed relative to the calcination temperature and carbon fiber (CF) content. The findings reveal that, when maintained at an optimal temperature, a specific quantity of CF introduced serves multiple functions: it acts as a structural template, imparting a hollow-fiber hierarchical morphology to the resulting materials, while also facilitating the reduction of Ni2+ to Ni0 through carbonization. Additionally, it supplies carbon, enabling the formation of multicomponent materials composed of Ni0, NiO, and C. These materials really shine due to their magnetic nature, their ability to soak up other substances, and their knack for speeding up electrical reactions. They are particularly good at both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER), which makes them a killer combo for splitting water into its basic elements. The unique layered structure and cooperative action of Ni0 and NiO significantly improve the synthesized material's performance in both the OER and HER. Notably, this preparation method is affordable, straightforward, and sustainable and has an abundant, renewable template source.

In this study, we developed a novel Sn quantum dot-loaded N-and O-containing biochar composite (Sn-QDs/ CNO) using pomelo peel as the main raw material via a solvothermal-pyrolysis method. The composite exhibited exceptional adsorption and UV-/Vis-light photocatalytic performance. Optimal synthesis parameters were determined as 750 degrees C, pH= 7.0, and 0.5000 g of biomass. During pyrolysis, the biomass was converted into conjugated N/O-containing biochar (CNO), which reduced the Sn3O4/SnO2 formed in the solvothermal reaction to metallic Sn. Within the studied temperature range, the highest defect concentration and optimal performance were achieved at approximately 750 degrees C. The presence of defects indicates the formation of strong interactions/ heterojunctions between Sn-QDs and biochar, enhancing rapid charge transfer and separation, thereby improving photocatalytic performance. Under mercury lamp irradiation, the optimal composite Sn-QDs/CNO750 achieved 99 % removal efficiency of MB (100 mg/L) within 60 minutes, with a first-order kinetic constant of 0.081 min(-1). This excellent performance can be attributed to the fact that under light irradiation, electron transitions occur across bands of varying energies in metallic Sn-QDs, generating e(-)-h(+) pairs that initiate oxidation-reduction reactions. The biochar exhibits a large active surface area and excellent charge transfer properties, enabling it to fully adsorb and activate pollutant molecules and achieve efficient separation of photogenerated e(-)-h(+) pairs through the migration of electrons from Sn to CNO. Active species such as center dot O2, center dot OH, e-, and h(+) were detected, with center dot OH and h(+) playing a dominant role. Adsorptive and photocatalytic degradation mechanism of the dye on the composite is proposed. Synopsis: This work successfully synthesized the Sn-QDs/CNO material, which exhibited excellent adsorptivephotocatalytic performance in removing organic dyes from wastewater.

Significant advancements have been made in the development of bifunctional electrocatalysts for the comprehensive water splitting in alkaline electrolytes. However, the creation of inexpensive, abundant, and efficient non-precious alternatives through effective strategies remains a formidable task. In this study, a simple impregnation-pyrolysis approach was employed to fabricate nitrogen-containing biochar-encapsulated cobalt nanoparticles supported on nitrogen-doped graphitic carbon electrocatalysts. By varying the pyrolysis temperature and the amount of grapefruit peel, the catalyst optimized under conditions of 700 degrees C and 2.5000 g of grapefruit peel exhibits the lowest overpotentials of 340 mV for the oxygen evolution reaction and 120 mV for the hydrogen evolution reaction at 10 mA cm-2 under alkaline conditions, respectively. Furthermore, it exhibits exceptional electrocatalytic stability, maintaining negligible overpotentials even after undergoing 2000 CV cycles, with good preservation of its structure and morphology. This study offers an environmentally friendly, and efficient approach for the fabrication of high-performance bifunctional electrocatalysts.

The development of efficient transition metal-based electrocatalysts is a prerequisite for use in OER and ORR, as well as for zinc-air batteries. However, it is still a great challenge to prepare durable and efficient electrocatalysts. In this part, in this paper, a composite (NiFeCo-P@NC) with bifunctional activity and relatively excellent battery performance was successfully designed and constructed by combining transition metal carbon matrix composites with low-temperature solid-phase phosphatisation. After electrochemical performance tests, we found that the material has excellent OER activity with eta 10 of 298 mV, which is better than commercial RuO2 (340 mV). In addition, NiFeCo-P@NC also showed satisfactory performance in the ORR test. It also exhibited excellent cycling stability (123h) when assembled into ZABs, while its power density was as high as 147.7 mW cm- 2, which was much larger than that of commercial Pt/C + RuO2 catalysts (108.1 mW cm- 2).

The integration of heterostructure engineering with carbon materials exhibits significant advantages in enhancing ion transport efficiency and stability, buffering volume changes, and improving electrochemical lithium/sodium storage performance of transition metal selenide electrodes. In this study, we employ binary metal-organic frameworks as the precursors to successfully prepare rod-shaped composites assembled by carbon-coated bimetallic heterostructure nanoparticles (Cu2-xSe/Bi2Se3@C) through a controlled selenization process at varying temperatures. The optimized Cu2-xSe/Bi2Se3@C-600 composite demonstrate exceptional lithium storage capabilities, achieving high reversible capacities of 1102.3 mAh g g-1 at 0.2 A g g-1 after 100 cycles and 640.6 mAh g g-1 at 1.0 A g g-1 after 500 cycles. Ex-situ XRD analysis and theoretical calculations are utilized to elucidate the electrochemical reaction mechanisms and the benefits of the heterointerface in enhancing performance. The density functional theory calculation results indicate that the heterointerface in Cu2-xSe/Bi2Se3 reduces diffusion energy barrier of surface Li + ions and enhances electronic conductivity. The unique structure and composition advantages also grant the optimal composite superior sodium storage performance with high specific capacity (442.7 mAh g g-1 at 0.2 A g g-1 after 100 cycles), exceptional rate capability (297.3 mAh g g-1 at 10.0 A g-1 1), and long-term cyclability (254.7 mAh g g-1 at 5.0 A g g-1 after 500 cycles).

It is necessary to develop and design transition trimetallic materials as electrocatalysts to solve the energy shortage problem in current society. Therefore, to address this problem, this paper proposes the formation of Co-N/C by high-temperature carbonation of precursors, followed by adsorption and chelation of Fe and Ni metal ions onto chitosan and encapsulation in Co-N/C and then the formation of electrocatalysts with Fe and Ni modifications to Co-N/C (CoFeNi-N/C) by further pyrolysis. It is worth finding that the coupling between Co-N/C and Fe and Ni-N/C can improve the catalytic performance of CoFeNi-N/C, and the ORR half-wave potential of the prepared catalyst (CoFeNi-N/C) can reach up to 0.841 V, and the OER overpotential at 10 mA cm-2 is 340 mV as measured experimentally.

The development of affordable electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) using non-precious metals creates opportunities to enhance fuel cell energy storage systems. In this paper, we report a surface cladding technique encapsulated in a heterostructure of nitrogen and cobalt self-doped carbon (NC-Co) to achieve highly efficient ORR and OER. CoMoO4 has exceptional electrical conductivity and catalytic activity because of its unique rod-like structure, which gives it a high specific surface area and more active sites. Moreover, the integration of CoMoO4 and NC-Co can enhance the heterostructures' conductivity by inducing electron redistribution and narrowing the band gap, which supports the improvement of the charge transfer kinetics of the heterostructures. Meanwhile, the obtained CoMoO4@NC-Co exhibits strong bifunctional ORR/OER activity and stability by optimizing the structure and positive interaction between CoMoO4 and NC-Co layers. More significantly, compared to conventional Pt/C batteries, the zinc-air batteries (ZABs) built using CoMoO4@NC-Co demonstrated greater specific capacity (814 mAh g-1) and extended cycle life. This paper's study suggests a possible use for ZABs as well as a logical path for creating very effective rare earth catalysts.