材料导报:能源(英文)最新文献

Photocatalytic water splitting by semiconductors is a promising technology to produce clean H₂ fuel, but the efficiency is restrained seriously by the high overpotential of the H₂-evolution reaction together with the high recombination rate of photoinduced charges. To enhance H₂ production, it is highly desirable yet challenging to explore an efficient reductive cocatalyst and place it precisely on the right sites of the photocatalyst surface to work the proton reduction reaction exclusively. Herein, the metalloid Ni_xP cocatalyst is exactly positioned on the Z-scheme Cd_0.5Zn_0.5S/NiTiO₃ (CZS/NTO) heterostructure through a facile photodeposition strategy, which renders the cocatalyst form solely at the electron-collecting locations. It is revealed that the directional transfer of photoexcited electrons from Cd_0.5Zn_0.5S to Ni_xP suppresses the quenching of charge carriers. Under visible light, the CZS/NTO hybrid loaded with the Ni_xP cocatalyst exhibits an optimal H₂ yield rate of 1103 μmol h⁻¹ (i.e., 27.57 mmol h⁻¹ g⁻¹), which is about twofold of pristine CZS/NTO and comparable to the counterpart deposited with the Pt cocatalyst. Besides, the high apparent quantum yield (AQY) of 56% is reached at 400 nm. Further, the mechanisms of the cocatalyst formation and the H₂ generation reaction are discussed in detail.

Due to the abundance and sustainability of solar energy, converting it into chemical energy to obtain clean energy presents an ideal solution for addressing environmental pollution and energy shortages stemming from the extensive combustion of fossil fuels. In recent years, hydrogen energy has emerged on the stage of history as the most promising clean energy carrier of the 21st century. Among the current methods of producing hydrogen, photocatalytic hydrogen production technology, as a zero-carbon approach to producing high calorific value and pollution-free hydrogen energy, has attracted much attention since its discovery. As the core of photocatalysis technology, semiconductor photocatalysts are always the research hotspots. Among them, graphite-phase carbon nitride (g-C₃N₄), an organic semiconductor material composed of only C and N elements, possesses physicochemical properties incomparable to those of traditional inorganic semiconductor materials, including suitable energy band positions, easy structural regulation, inexpensive raw materials and abundant reserves, simple preparation, high thermal/mechanical/chemical stability, etc. Therefore, g-C₃N₄ has attracted extensive attention in the field of photocatalytic hydrogen production in the last two decades. This review comprehensively outlines the research trajectory of g-C₃N₄ photocatalytic hydrogen production, encompassing development, preparation methods, advantages, and disadvantages. A concise introduction to g-C₃N₄ is provided, as well as an analysis of the underlying mechanism of the photocatalytic system. Additionally, it delves into the latest techniques to enhance performance, including nanostructure design, elemental doping, and heterojunction construction. The applications of g-C₃N₄ based photocatalysts in hydrogen production are surveyed, underscoring the significance of catalyst active sites and g-C₃N₄ synthesis pathways. At length, concluded are insights into the challenges and opportunities presented by g-C₃N₄ based photocatalysts for achieving heightened hydrogen production.

Bismuth vanadate (BiVO₄) is an excellent photoanode material for photoelectrochemical (PEC) water splitting system, possessing high theoretical photoelectrocatalytic conversion efficiency. However, the actual PEC activity and stability of BiVO₄ are faced with great challenges due to factors such as severe charge recombination and slow water oxidation kinetics at the interface. Therefore, various interface regulation strategies have been adopted to optimize the BiVO₄ photoanode. This review provides an in-depth analysis for the mechanism of interface regulation strategies from the perspective of factors affecting the PEC performance of BiVO₄ photoanodes. These interface regulation strategies improve the PEC performance of BiVO₄ photoanode by promoting charge separation and transfer, accelerating interfacial reaction kinetics, and enhancing stability. The research on the interface regulation strategies of BiVO₄ photoanode is of great significance for promoting the development of PEC water splitting technology. At the same time, it also has inspiration for providing new ideas and methods for designing and preparing efficient and stable catalytic materials.

Extremely high-temperature and high-pressure requirement of Haber-Bosch process motivates the search for a sustainable ammonia synthesis approach under mild conditions. Photocatalytic technology is a potential solution to convert N₂ to ammonia. However, the poor light absorption and low charge carrier separation efficiency in conventional semiconductors are bottlenecks for the application of this technology. Herein, a facile synthesis of anatase TiO₂ nanosheets with an abundance of surface oxygen vacancies (TiO₂-OV) via the calcination treatment was reported. Photocatalytic experiments of the prepared anatase TiO₂ samples showed that TiO₂-OV nanosheets exhibited remarkably increased ammonia yield for solar-driven N₂ fixation in pure water, without adding any sacrificial agents. EPR, XPS, XRD, UV-Vis DRS, TEM, Raman, and PL techniques were employed to systematically explore the possible enhanced mechanism. Studies revealed that the introduced surface oxygen vacancies significantly extended the light absorption capability in the visible region, decreased the adsorption and activation barriers of inert N₂, and improved the separation and transfer efficiency of the photogenerated electron-hole pairs. Thus, a high rate of ammonia evolution in TiO₂-OV was realized. This work offers a promising and sustainable approach for the efficient artificial photosynthesis of ammonia.

Photocatalytic water splitting on noble metal-free photocatalysts for H₂ generation is a promising but challenging approach to realize solar-to-chemical energy conversion. In this study, Mo/Mo₂C nanoparticles anchored carbon layer (Mo/Mo₂C@C) was obtained by a one-step in-situ phase transition approach and developed for the first time as a photothermal cocatalyst to enhance the activity of ZnIn₂S₄ photocatalyst. Mo/Mo₂C@C nanosheet exhibits strong absorption in the full spectrum region and excellent photo-thermal conversion ability, which generates heat to improve the reaction temperature and accelerate the reaction kinetics. Moreover, metallic Mo/Mo₂C@C couples with ZnIn₂S₄ to form ZnIn₂S₄–Mo/Mo₂C@C Schottky junction (denoted as ZMM), which prevents the electrons back transfer and restrains the charge recombination. In addition, conductive carbon with strong interfacial interaction serves as a fast charge transport bridge. Consequently, the optimized ZMM-0.2 junction exhibits an H₂ evolution rate of 1031.07 μmol g⁻¹ h⁻¹, which is 41 and 4.3 times higher than bare ZnIn₂S₄ and ZnIn₂S₄–Mo₂C, respectively. By designing novel photothermal cocatalysts, our work will provide a new guidance for designing efficient photocatalysts.

Photoelectrochemical reduction of CO₂ to produce CO with metal-organic frameworks (MOFs) is recognized as a desirable technology to mitigate CO₂ emission and generate sustainable energy. To achieve highly efficient electrocatalyst, it is essential to design a new material interface and uncover new reaction mechanisms or kinetics. Herein, we developed two metal-organic Cu-MOF and Bi-MOF layers using benzene tricarboxylic acid (H₃BTC) ligands on CuBi₂O₄ photocathodes. Both MOF layers drastically improved the photoelectrochemical stability by suppressing the photo-corrosion through conformal surface passivation. The Cu-MOF modified CuBi₂O₄ showed more significant charge separation and transfer efficiencies than the Bi-MOF modified control. Based on the transient photocurrent curves under the applied potential of 0.6 V vs. RHE, the rate-law analysis showed the CO₂ photoreduction took place through a first-order reaction. Further, the photoelectrochemical impedance spectra (PEIS) revealed this reaction order, representing an “operando” analysis. Moreover, the reaction rate constant on Cu-MOF modified sample was higher than that on Bi-MOF modified one and bare CuBi₂O₄. Combined with the density functional theory calculation, the surface absorption of CO₂ and CO molecules and the higher energy barrier for ∗COOH intermediates could significantly determine the first order reaction.

Copper (Cu) is extensively employed in photocatalytic CO₂ reduction reactions for the production of high-value products. The valence state of transition metals plays a pivotal role in influencing the catalytic process. However, due to the complex valence state changes of Cu in the CO₂ reduction reaction, research on its valence state effect is lacking. The current work is to prepare a series of TiO₂/CuX with stable Cu valence composition using different copper halides (CuX and CuX₂, X = Br or Cl) as precursors. The results show that the CuBr₂ loading leads to Cu⁺/Cu²⁺ mixed cocatalyst and exhibits the highest activity for CO₂ photoreduction. The CH₄ evolution rate of the TiO₂/CuBr₂ catalyst is as high as 100.59 μmol h⁻¹ g⁻¹, which is 6.6 times that of pristine TiO₂. The CH₄ selectivity reaches 77%. The enhanced catalytic activity and selectivity can be ascribed to the efficient surface adsorption, activation, excellent carrier separation, and transfer of Cu⁺/Cu²⁺ mixed cocatalyst. Our findings provide a reference for designing highly active Cu-based photocatalysts.

Co₃O₄ was synthesized on carbon paper (CP) using a facile method to improve electrochemical nitrate-to-ammonia conversion efficiency. The resulting Co₃O₄-CP electrode demonstrated an exceptional Faradaic efficiency of almost 100% across a broad range of application conditions, with a peak NH₃ yield of 3.43 mmol h⁻¹ cm⁻² (2.25 mol g_Co⁻¹ h⁻¹).