Frontiers in Energy最新文献

Metal-free graphitic carbon nitride (g-C₃N₄) has captured significant attention as a low-cost and efficient hydrogen production photocatalyst through. Effectively regulating the microstructure and accelerating the separation of photogenerated carriers remain crucial strategies for promoting the photocatalytic performance of this material. Herein, a novel sulfur–carbon co-doped g-C₃N₄ (SCCN) hierarchical microtubules filled with abundant nanosheets inside by thermal polymerization is reported. Numerous nanosheets create abundant pores and cavities inside the SCCN microtubes, thereby increasing the specific surface area of g-C₃N₄ and providing sufficient reactant attachment sites. Besides, the hierarchical structure of SCCN microtubules strengthens the reflection and scattering of light, and the utilization of visible light is favorably affected. More importantly, co-doping S and C has greatly improved the photocatalytic performance of graphitic carbon nitride, optimized the band gap structure and enhanced the photogenerated carrier splitting. Consequently, the SCCN exhibits a remarkable photocatalytic H₂ evolution rate of 4868 µmol/(g·h). This work demonstrates the potential of multi-nonmetal doped g-C₃N₄ as the ideal photocatalyst for H₂ evolution.

The automotive industry is in the midst of a groundbreaking revolution, driven by the imperative to achieve intelligent driving and carbon neutrality. A crucial aspect of this transformation is the transition to electric vehicles (EVs), which necessitates widespread changes throughout the entire automotive ecosystem. This paper examines the challenges and opportunities of this transition, including automotive electrification, intelligence-connected transportation system, and the potential for new technologies such as hydrogen fuel cells. Meanwhile, it discusses the key technologies and progress of the hydrogen energy industry chain in the upstream hydrogen production, midstream hydrogen storage and transportation, downstream hydrogen station construction and hydrogen fuel cells in turn. Finally, it proposes the directions for future layout, providing guidance for future development.

Electrocatalytic CO₂ reduction (ECR) offers an attractive approach to realizing carbon neutrality and producing valuable chemicals and fuels using CO₂ as the feedstock. However, the lack of cost-effective electrocatalysts with better performances has seriously hindered its application. Herein, a one-step co-electrodeposition method was used to introduce Zn, a metal with weak *CO binding energy, into Cu to form Cu/Zn intermetallic catalysts (Cu/Zn IMCs). It was shown that, using an H-cell, the high Faradaic efficiency of C₂₊ hydrocarbons/alcohols (({rm{F}}{{rm{E}}_{{{rm{C}}_{2 + }}}})) could be achieved in ECR by adjusting the surface metal components and the applied potential. In suitable conditions, FE_C2+ and current density could be as high as 75% and 40 mA/cm², respectively. Compared with the Cu catalyst, the Cu/Zn IMCs have a lower interfacial charge transfer resistance and a larger electrochemically active surface area (ECSA), which accelerate the reaction. Moreover, the *CO formed on Zn sites can move to Cu sites due to its weak binding with *CO, and thus enhance the C–C coupling on the Cu surface to form C₂₊ products.

A thorough analysis of triboelectric nanogenerators (TENGs) that make use of self-healable nanomaterials is presented in this review. These TENGs have shown promise as independent energy sources that do not require an external power source to function. TENGs are developing into a viable choice for powering numerous applications as low-power electronics technology advances. Despite having less power than conventional energy sources, TENGs do not directly compete with these. TENGs, on the other hand, provide unique opportunities for future self-powered systems and might encourage advancements in energy and sensor technologies. Examining the many approaches used to improve nanogenerators by employing materials with shape memory and self-healable characteristics is the main goal of this review. The findings of this comprehensive review provide valuable information on the advancements and possibilities of TENGs, which opens the way for further research and advancement in this field. The discussion of life cycle evaluations of TENGs provides details on how well they perform in terms of the environment and identifies potential improvement areas. Additionally, the cost-effectiveness, social acceptability, and regulatory implications of self-healing TENGs are examined, as well as their economic and societal ramifications.

Plastic waste is causing serious environmental problems. Developing efficient, cheap and stable catalytic routes to convert plastic waste into valuable products is of great importance for sustainable development, but remains to be a challenging task. Zeolites are cheap and stable, but they are usually not efficient for plastic conversion at a low temperature. Herein a series of microporous and mesoporous zeolites were used to study the influence of porosity and acidity of zeolite on catalytic activity for plastics conversion. It was observed that H-Beta zeolite was an efficient catalyst for cracking high-density polyethylene to gasoline at 240 °C, and the products were almost C₄-C₁₂ alkanes. The effect of porosity and acidity on catalytic performance of zeolites was evaluated, which clearly visualized the good performance of H-Beta due to high surface area, large channel system, large amount accessible acidic sites. This study provides very useful information for designing zeolites for efficient conversion of plastics.

Dehydrogenation of formic acid (FA) is considered to be an effective solution for efficient storage and transport of hydrogen. For decades, highly effective catalysts for this purpose have been widely investigated, but numerous challenges remain. Herein, the Pd_xAu_1−x (x = 0, 0.2, 0.4, 0.5, 0.6, 0.8, 1) alloys over the whole composition range were successfully prepared and used to catalyze FA hydrogen production efficiently near room temperature. Small PdAu nanoparticles (5–10 nm) were well-dispersed and supported on the activated carbon to form PdAu solid solution alloys via the eco-friendly slow synthesis methodology. The physicochemical properties of the PdAu alloys were comprehensively studied by utilizing various measurement methods, such as X-ray diffraction (XRD), N₂ adsorption–desorption, high angle annular dark field-scanning transmission electron microscope (HAADF-STEM), X-ray photoelectrons spectroscopy (XPS). Notably, owing to the strong metal-support interaction (SMSI) and electron transfer between active metal Au and Pd, the Pd_0.5Au_0.5 obtained exhibits a turnover frequency (TOF) value of up to 1648 h⁻¹ (313 K, n_Pd+Au/n_FA = 0.01, n_HCOOH/n_HCOONa = 1:3) with a high activity, selectivity, and reusability in the FA dehydrogenation.

It has been widely reported that, for faceted nanocrystals, the two adjacent facets with different band levels contribute to promoted charge separation, and provide active sites for photocatalytic reduction and oxidation reaction, respectively. In such cases, only one family of facets can be used for photocatalytic hydrogen evolution. Herein, by using SrTiO₃ nanocrystals enclosed by {023} and {001} facets as a model photocatalyst, this paper proposed a strategy to achieve the full-facets-utilization of the nanocrystals for photocatalytic hydrogen via chemically depositing Pt nanoparticles on all facets. The photo-deposition experiment of CdS provided direct evidence to demonstrate that the {023} facets which were responsible for photooxidation reaction can be function-reversed for photocatalytic hydrogen evolution after depositing Pt nanoparticles, together with the {001} facets. Thus, the full-facets-utilization led to a much-improved activity for photocatalytic hydrogen, in contrast to those SrTiO₃ nanocrystals with only {001} facets deposited by Pt nanoparticles via a photo-deposition method.

Hydrogen production from photoelectrochemical (PEC) water splitting has been regarded as a promising way to utilize renewable and endless solar energy. However, semiconductor film grown on photoelectrode suffers from numerous challenges, leading to the poor PEC performance. Herein, a straightforward sol-gel method with the ligand-induced growth strategy was employed to obtain dense and homogeneous copper bismuthate photocathodes for PEC hydrogen evolution reaction. By various characterizations, it was found that the nucleation and surface growth of CuBi₂O₄ layer induced by 2-methoxyethanol ligand (2-CuBi₂O₄) demonstrated a decent crystallinity and coverage, as well as a large grain size and a low oxygen vacancy concentration, leading to the good ability of light absorption and carrier migration. Consequently, under simulated sunlight irradiation (AM1.5G, 100 mW/cm²), the 2-CuBi₂O₄ photocathode achieved an enhanced photocurrent density of −1.34 mA·cm⁻² at 0.4 V versus the reversible hydrogen electrode and a promising applied bias photon-to-current efficiency of 0.586%. This surface modification by ligand growth strategy will shed light on the future design of advanced photoelectrodes for PEC water splitting.

Production of hydrogen, one of the most promising alternative clean fuels, through catalytic conversion from fossil fuel is the most technically and economically feasible technology. Catalytic conversion of natural gas into hydrogen and carbon is thermodynamically favorable under atmospheric conditions. However, using noble metals as a catalyst is costly for hydrogen production, thus mandating non-noble metal-based catalysts such as Ni, Co, and Cu-based alloys. This paper reviews the various hydrogen production methods from fossil fuels through pyrolysis, partial oxidation, autothermal, and steam reforming, emphasizing the catalytic production of hydrogen via steam reforming of methane. The multicomponent catalysts composed of several nonnoble materials have been summarized. Of the Ni, Co, and Cu-based catalysts investigated in the literature, Ni/Al₂O₃ catalyst is the most economical and performs best because it suppresses the coke formation on the catalyst. To avoid carbon emission, this method of hydrogen production from methane should be integrated with carbon capture, utilization, and storage (CCUS). Carbon capture can be accomplished by absorption, adsorption, and membrane separation processes. The remaining challenges, prospects, and future research and development directions are described.

High entropy materials (HEMs) have developed rapidly in the field of electrocatalytic water-electrolysis for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) due to their unique properties. In particular, HEM catalysts are composed of many elements. Therefore, they have rich active sites and enhanced entropy stability relative to single atoms. In this paper, the preparation strategies and applications of HEM catalysts in electrochemical water-electrolysis are reviewed to explore the stabilization of HEMs and their catalytic mechanisms as well as their application in support green hydrogen production. First, the concept and four characteristics of HEMs are introduced based on entropy and composition. Then, synthetic strategies of HEM catalysts are systematically reviewed in terms of the categories of bottom-up and top-down. The application of HEMs as catalysts for electrochemical water-electrolysis in recent years is emphatically discussed, and the mechanisms of improving the performance of electrocatalysis is expounded by combining theoretical calculation technology and ex-situ/in situ characterization experiments. Finally, the application prospect of HEMs is proposed to conquer the challenges in HEM catalyst fabrications and applications.