Solar‐driven water electrolysis has been considered to be a promising route to produce green hydrogen, because the conventional water electrolysis system is not completely renewable as it requires ...power from nonrenewable fossil fuel sources. This review emphasizes the strategies for solar‐driven water electrolysis, including the construction of photovoltaic (PV)‐water electrolyzer systems, PV‐rechargeable energy storage device‐water electrolyzer systems with solar energy as the sole input energy, and photoelectrochemical water splitting systems. The basic discussions of the above strategies for solar‐driven water electrolysis are first presented. Meanwhile, replacing the oxygen evolution reaction with the electrooxidation of organic compounds can effectively improve the efficiency of water splitting. Also, solar‐driven seawater electrolysis greatly broadens the practical applications due to the abundant reserves of seawater. Recent years have witnessed great development in the field of solar‐driven water electrolysis. The recent research development in the area is subsequently reviewed. Finally, perspectives on the existing challenges along with some opportunities for the further development of solar‐driven water electrolysis are provided.
This review discusses the strategies for solar‐driven water electrolysis including the construction of photovoltaic (PV)‐water electrolyzer systems, PV‐rechargeable energy storage device‐water electrolyzer systems with solar energy as the sole input energy, and photoelectrochemical (PEC) water splitting systems. The advances in organic compound‐assisted water splitting systems and solar‐driven seawater electrolysis systems are also given.
Over the past decade, transition metal phosphate materials have attracted enormous interest for various functional devices. In addition to being low‐cost, earth‐abundant and environmentally benign, ...transition metal phosphates have several unique advantages including high stability, unique chemical/physical characteristics and tunable multifunctionality, making them ideally suited for advanced highly‐efficiency energy conversion and storage applications. In this Review, the synthetic strategies for transition metal phosphates are summarized, and the most recent advances in the development of transition metal phosphates are described for efficient electrocatalysis such as oxygen evolution, hydrogen evolution and oxygen reduction reactions, highlighting the impact of their morphologies and structures on the electrochemical performance and practical applications in overall water splitting and rechargeable metal‐air batteries. Finally, the challenges facing the development of transition metal phosphates in the field of energy conversion and storage are outlined, together with directions of further research and perspectives.
Earth‐abundant electrocatalysts: The synthetic strategies and the most recent advances of transition metal phosphates for efficient electrocatalysis are reviewed, highlighting the impact of their morphologies and structures on electrochemical performance. The challenges facing their development in the hydrogen‐ and oxygen‐involving electrocatalytic reactions are outlined, together with directions of further research and perspectives.
Hydrogen peroxide (H2O2) is a highly value‐added and environmentally friendly chemical with various applications. The production of H2O2 by electrocatalytic 2e− oxygen reduction reaction (ORR) has ...drawn considerable research attention, with a view to replacing the currently established anthraquinone process. Electrocatalysts with low cost, high activity, high selectivity, and superior stability are in high demand to realize precise control over electrochemical H2O2 synthesis by 2e− ORR and the feasible commercialization of this system. This Review introduces a comprehensive overview of non‐noble metal‐based catalysts for electrochemical oxygen reduction to afford H2O2, providing an insight into catalyst design and corresponding reaction mechanisms. It starts with an in‐depth discussion on the origins of 2e−/4e− selectivity towards ORR for catalysts. Recent advances in design strategies for non‐noble metal‐based catalysts, including carbon nanomaterials and transition metal‐based materials, for electrochemical oxygen reduction to H2O2 are then discussed, with an emphasis on the effects of electronic structure, nanostructure, and surface properties on catalytic performance. Finally, future challenges and opportunities are proposed for the further development of H2O2 electrogeneration through 2e− ORR, from the standpoints of mechanistic studies and practical application.
Nobility not required: Hydrogen peroxide is a highly value‐added and environmentally friendly chemical with various applications. This Review summarizes various strategies for the engineering of non‐noble metal‐based catalysts to generate hydrogen peroxide by electrochemical oxygen reduction. Some insights into future directions are also proposed and discussed.
The key challenge to developing renewable energy conversion and storage devices lies in the exploration and rational engineering of cost‐effective and highly efficient electrocatalysts for various ...energy‐related electrochemical reactions. Transition‐metal phosphates and phosphonates have shown remarkable performances for these reactions based on their unique physicochemical properties. Compared with transition‐metal oxides, phosphate groups in transition‐metal phosphates and phosphonates show flexible coordination with diverse orientations, making them an ideal platform for designing active electrocatalysts. Although numerous efforts have been spent on the development of transition‐metal phosphate and phosphonate electrocatalysts, some urgent issues, such as low intrinsic catalytic efficiency and low electronic conductivity, have to be resolved in accordance with their applications. In this Review, we focus on the design strategies of highly efficient transition‐metal phosphate and phosphonate electrocatalysts, with special emphasis on the tuning of transition‐metal‐center coordination environment, optimization of electronic structures, increase of catalytically active site densities, and construction of heterostructures. Guided by these strategies, recently developed transition‐metal phosphate and phosphonate materials have exhibited excellent activity, selectivity, and stability for various energy‐related electrocatalytic reactions, showing great potential for replacing noble‐metal‐based catalysts in next‐generation advanced energy techniques. The existing challenges and prospects regarding these materials are also presented.
Phosphorus the true hero: In this Review, the recent progresses of engineering strategies for high‐efficiency transition‐metal phosphate and phosphonate electrocatalysts towards sustainable energy devices are summarized, including regulation of transition‐metal center coordination environment, optimization of electronic structure, increase of catalytically active site density, and construction of heterostructure. Some insights into future directions are also proposed and discussed.
Recent years have witnessed an upsurge of interest in exploiting advanced photo‐/electrocatalysts for efficient energy conversion and environmental remediation. Constructing internal electric fields ...has been highlighted as a rising star to help facilitate various catalytic processes, with the merits of promoting charge transfer/separation, optimizing redox potential and creating effective active/adsorption sites. Internal electric fields are usually formed by the polarization of uneven charge distributions between different constituent layers, which widely exist in piezoelectrics, polar surface terminations, and heterostructure materials. Herein, a groundbreaking and interdisciplinary overview of the latest advances in the construction of internal electric fields to improve photo(electro)catalytic and electrocatalytic activity is provided. This critical review begins with an encyclopedic summary of the classification, advantages, and synthesis strategies of internal electric fields. Subsequently, the identification methods are thoroughly discussed based on the characterization techniques, experiments, and theoretical calculations, which can provide profound guidance for the in‐depth study of internal electric fields. To elaborate the theory–structure–activity relationships for internal electric fields, the corresponding reaction mechanisms, modification strategies, and catalytic performance are jointly discussed, along with a discussion of their practical energy and environmental applications. Finally, an insightful analysis of the challenges and future prospects for internal electric field‐based catalysts are discussed.
This review provides a clear understanding of the classification, advantages, creation, and identification of internal electric fields and the dramatic improvements in energy and environmental catalysis that result.
As hydrogen has been increasingly considered as promising sustainable energy supply, electrochemical overall water splitting driven by highly efficient non‐noble metal electrocatalysts has aroused ...extensive attention. Transition metal phosphides (TMPs) have demonstrated remarkable electrocatalytic performance, including high activity and robust durability towards hydrogen evolution reaction (HER) in acidic and alkaline as well as neutral electrolytes. In this Review, up‐to‐date progress of TMP‐based HER electrocatalysts is summarized. Various synthesis strategies of TMPs based on selected phosphorus sources are presented, and the reaction mechanisms of HER as well as the contribution of phosphorus in the TMPs to HER activity are briefly discussed. The multiscale approaches for promoting the activity and stability of TMP‐based catalysts are discussed with respect to intrinsic electronic structure, hybrids, microstructure, and working electrode interface. Some crucial issues and future perspectives of TMPs are pointed out. These modulated approaches and challenges are also instructive for constructing other high‐activity energy‐related electrocatalysts.
Transitioning to hydrogen: In this Review, up‐to‐date progress of transition metal phosphide (TMP)‐based hydrogen evolution reaction (HER) electrocatalysts is summarized. Various synthesis strategies and the HER reaction mechanisms of TMP‐based catalysts are briefly discussed. In addition, multiscale approaches with respect to electronic structure, hybrids, microstructure, and working electrode interface are discussed for promoting HER performances.
We propose a new neutron-capture site in early metal-poor and metal-free stars of ∼20-30 M that results from proton ingestion in the He shell during late stages of the stars' lives. Most of the ...neutron capture occurs in the first 106 s following proton ingestion when 13C( , n)16O produces neutron densities typical of the intermediate neutron-capture process. This phase may be followed by another lasting 107 s with 17O( , n)20Ne producing much lower neutron densities typical of the slow neutron-capture process. We explore the dependence of the proposed neutron-capture nucleosynthesis on the amount and time of proton ingestion, the initial metallicity, and the ensuing supernova shock. We obtain a range of heavy-element abundance patterns, including those attributed to the slow neutron-capture process or a combination of the slow and rapid neutron-capture processes. Our results can account for the observed ubiquity of heavy elements such as Sr and Ba in the early Galaxy and explain puzzling abundance patterns of these elements in at least some very metal-poor (VMP) stars, including those of the carbon-enhanced varieties. In the latter case, the explanation by the single site proposed here differs from the existing paradigm that attributes various classes of VMP stars to enrichment by multiple different sites.
The wind driven by the intense neutrino emission from a protoneutron star (PNS) is an important site for producing nuclei heavier than the Fe group. Because of certain features in the neutrino ...angular distributions, the so-called fast flavor oscillations may occur very close to the PNS surface, effectively resetting the neutrino luminosities and energy spectra that drive the wind. Using the unoscillated neutrino emission characteristics from two core-collapse supernova simulations representative of relevant progenitors at the lower and higher mass end, we study the potential effects of fast flavor oscillations on neutrino-driven winds and their nucleosynthesis. We find that such oscillations can increase the total mass loss by factors up to ∼1.5-1.7 and lead to significantly more proton-rich conditions. The latter effect can greatly enhance the production of 64Zn and the so-called light p-nuclei 74Se, 78Kr, and 84Sr. Implications for abundances in metal-poor stars, Galactic chemical evolution in general, and isotopic anomalies in meteorites are discussed.
Water splitting for the production of hydrogen and oxygen is an appealing solution to advance many sustainable and renewable energy conversion and storage systems, while the key fact depends on the ...innovative exploration regarding the design of efficient electrocatalysts. Reported herein is the growth of CoP mesoporous nanorod arrays on conductive Ni foam through an electrodeposition strategy. The resulting material of well‐defined mesoporosity and a high specific surface area (148 m2 g−1) can be directly employed as a bifunctional and flexible working electrode for both hydrogen and oxygen evolution reactions, showing superior activities as compared with noble metal benchmarks and state‐of‐the‐art transition‐metal‐based catalysts. This is intimately related to the unique nanorod array electrode configuration, leading to excellent electric interconnection and improved mass transport. A further step is taken toward an alkaline electrolyzer that can achieve a current density of 10 mA cm−2 at a voltage around 1.62 V over a long‐term operation, better than the combination of Pt and IrO2. This development is suggested to be readily extended to obtain other electrocatalysis systems for scale‐up water‐splitting technology.
Flexible, bifunctional electrodes with self‐supported CoP mesoporous nanorod arrays are fabricated through an electrodeposition strategy. The electrodes possess well‐structured mesoporosity and a high specific surface area, exhibiting high activities toward both electrochemical hydrogen and oxygen evolution reactions. In a further step, an alkaline electrolyzer with a current density of 10 mA cm−2 at 1.62 V in a long‐term operation is realized.
Photocatalytic hydrogen production is crucial for solar‐to‐chemical conversion process, wherein high‐efficiency photocatalysts lie in the heart of this area. A photocatalyst of hierarchically ...mesoporous titanium phosphonate based metal–organic frameworks, featuring well‐structured spheres, a periodic mesostructure, and large secondary mesoporosity, are rationally designed with the complex of polyelectrolyte and cathodic surfactant serving as the template. The well‐structured hierarchical porosity and homogeneously incorporated phosphonate groups can favor the mass transfer and strong optical absorption during the photocatalytic reactions. Correspondingly, the titanium phosphonates exhibit significantly improved photocatalytic hydrogen evolution rate along with impressive stability. This work can provide more insights into designing advanced photocatalysts for energy conversion and render a tunable platform in photoelectrochemistry.
A multi‐structured photocatalyst: A metal–organic framework (MOF) nanostructure synthesized by a surfactant‐directed strategy features a stable framework of titanium phosphates, a well‐defined sphere, and hierarchical nanopores. These features ensure competitive photoactivity in evolving hydrogen under both visible light and full‐spectrum simulator irradiation, along with high durability.
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