中空碳基材料在电解水中的研究进展

氢能所具有的清洁、高能量密度特点，使其成为一种未来的理想能源。相较于石油、天然气等的热解制氢技术，利用可再生清洁能源进行电催化分解水制氢具有高效和清洁无污染的特点，且获得氢气产物纯度高，具备大规模发展的潜力。而在大规模水电解过程中，电催化剂是不可或缺的元素之一。它能有效地加速电解水在阴阳两极反应的动力学过程。传统的贵金属基催化剂具有良好的电催化析氢、析氧活性，但成本高昂、储量稀缺，从而限制了其规模化地推广及应用。开发新型高效廉价的非贵金属基电催化剂已成为时下研究热点。中空碳基纳米材料集成了中空材料和碳基材料的优势，作为电催化剂，在电解水方面有着潜在的应用价值。本文总结了近年来微纳米结构碳基中空材料作为新型电解水催化剂的研究进展，介绍了高效碳基中空析氧/析氢催化剂的设计原则和相应的设计策略，并对开发持久高效的中空碳基电解水催化剂进行了总结和展望。     

Layered double hydroxide-based core-shell nanoarrays for efficient electrochemical water splitting

Electrochemical water splitting is an efficient and clean strategy to produce sustainable energy productions (especially hydrogen) from earth-abundant water. Recently, layered double hydroxide (LDH)-based materials have gained increasing attentions as promising electrocatalysts for water splitting. Designing LDHs into hierarchical architectures (e.g., core-shell nanoarrays) is one of the most promising strategies to improve their electrocatalytic performances, owing to the abundant exposure of active sites. This review mainly focuses on recent progress on the synthesis of hierarchical LDH-based core-shell nanoarrays as high performance electrocatalysts for electrochemical water splitting. By classifying different nanostructured materials combined with LDHs, a number of LDH-based core-shell nanoarrays have been developed and their synthesis strategies, structural characters and electrochemical performances are rationally described. Moreover, further developments and challenges in developing promising electrocatalysts based on hierarchical nanostructured LDHs are covered from the viewpoint of fundamental research and practical applications.     

基于过渡金属电催化析氢催化剂的研究进展

随着人口快速增加,开发可持续能源已经成为当今世界的首要任务之一。氢气被认为是一种无污染、可再生的新能源,可以代替化石能源。氢气可以由电解水的电催化析氢半反应获得。传统的电催化析氢催化剂主要由贵金属构成,而贵金属稀少,价格昂贵,不适合大规模工业制氢。探索高效的非贵金属电催化析氢反应催化剂十分必要。基于过渡金属开发的电催化析氢反应催化剂引起广泛关注,综述基于过渡金属电催化析氢反应催化剂的研究进展,概述电解水原理,讨论基于过渡金属化物的电催化析氢反应催化剂材料的制备方法,包括硫化物、硒化物、碳化物、氮化物、磷化物及其复合物。探讨增强催化剂电催化析氢活性的方法及基于非贵金属电催剂材料面临的挑战和前景展望。     

Dual role of Fe boost lattice oxygen oxidation of Mo-based materials from kinetics and thermodynamics

High-valent Mo-based oxides are easily dissolved in alkaline electrolyte resulting in complete surface reconstruction of catalyst. Therefore, there are few researches on the oxygen evolution reaction (OER) process of this material, especially the reaction mechanism. Herein, Fe-Mo₂C@CN was synthesized by introducing 3d metal Fe into the Mo-based catalyst, which inhibited the complete dissolution of Mo. The overpotential is only 226 mV at a current density of 10 mA cm⁻². Experimental and density functional theory (DFT) results demonstrate that excellent electrocatalytic performance derives from the dual role of Fe and the thermodynamically favorable single-site lattice oxygen oxidation mechanism (LOM). Electronic-rich pure Fe inhibits the molybdenum dissolution while enhancing the reaction kinetics. And the doped Fe decreases the d‐band center, weakens the M-O (metal-oxygen) bond, and promotes the involvement of lattice oxygen in the OER process. This work provides theoretical basis for the engagement of Mo-based catalysts in water splitting.     

Interface engineering of copper-cobalt based heterostructure as bifunctional electrocatalysts for overall water splitting

It is of great significance to develop highly active and cost-effective electrocatalysts for the oxygen evolution reaction and hydrogen evolution reaction in alkaline solution. Herein, we report an interface engineering strategy to fabricate 3D hierarchical CuCo₂O₄@CuCo₂S₄ heterostructure catalysts with efficient synergistic effects for water splitting. Owing to the special nano-architectures with abundant active interfaces, the as-prepared CuCo₂O₄@CuCo₂S₄ catalysts exhibit superior electrochemical activity and prominent electrochemical stability, with a small overpotential of 240 and 101 mV for oxygen and hydrogen evolution reactions to deliver a current density of 10 mA cm⁻², respectively. Remarkably, the CuCo₂O₄@CuCo₂S₄ materials directly applied as both anode and cathode electrode demonstrate excellent water splitting performance, achieving 10 mA cm⁻² at a low cell voltage of only 1.53 V, outperforming the integrated state-of-the-art RuO₂||Pt/C couple (1.56 V). Moreover, density functional theory calculations suggest that the excellent overall water splitting property of CuCo₂O₄@CuCo₂S₄ is attributed to a large amount of hierarchical hetero-interfaces, giving rise to effective adsorption and cleavage of H₂O molecules on the catalyst surface. This work represents a general strategy to exploit efficient and stable hybrid electrocatalysts for renewable energy applications by rational catalyst interface engineering.     

电解水制氢MoS2催化剂研究与氢能技术展望

氢气具有质量轻、热值高、燃烧产物清洁等优点,被认为是理想的能源载体。氢气既能作为燃料电池的燃料,又能作为储能介质调节风能、太阳能发电系统的随机性、间歇性,正在成为未来能源的重要组成部分。为了促进电解水制氢技术与装备发展,研究高效电催化剂十分重要。本文围绕“粉末型”与“自支撑型”电催化剂结构特征,讨论基于二硫化钼（MoS₂）的析氢电催化剂的研究现状,阐述了催化活性位点调控策略与提高导电性两条技术途径,并以析氢过电位和塔菲尔曲线斜率为依据,比较不同方法制备的二硫化钼电催化剂的催化活性。表明提高二硫化钼晶相稳定性、调节其电子结构和优化催化电极结构等方法,将进一步提高基于二硫化钼的析氢催化电极性能。     

Hierarchical FeC/MnO2 composite with in-situ grown CNTs as an advanced trifunctional catalyst for water splitting and Metal−Air batteries

In high demand is developing trifunctional electrocatalysts to simultaneously drive hydrogen evolution reaction (HER) and oxygen evolution/reduction reaction (OER/ORR) for metal-air batteries and water splitting. Here we develop the carbon nanotubes (CNTs)-grafted FeC/MnO₂ nanocomposite catalyst by carbonizing FeMn metal-organic frameworks. The synergistic effect between FeC and MnO₂ dominantly contributes the ORR, OER, and HER. The transition metal-mediated growth of CNTs by an in-situ catalysis mechanism enables high electrical conductivity, abundant active sites, as well as efficient reaction pathways. The optimized chemical composite and unique hierarchical structure endow the FeC/MnO₂ with low overpotentials for multiply electrochemical reactions. Consequently, the composite catalyst successfully serves as the bifunctional electrode for water splitting with a voltage of 1.66 V at 10 mA cm^?2 as well as the cathode for all-solid-state metal-air battery with Pt/C-comparable performance. The advanced transition metal composite presented in this work provides the guidance for rationally developing trifunctional electrocatalysts for efficient integrated energy conversion systems.     

二硫化钼基全pH电催化析氢材料研究进展

电解水作为一种绿色制氢技术备受关注,设计开发适用于全pH（pH=0~14）介质的高效、低廉的电催化剂,可实现减少能耗、简化装置构建和优化生产工艺。二硫化钼具有电子结构的可调性以及除贵金属外最合适的热力学活性,是极具前景的析氢材料之一。通过综述二硫化钼基全pH析氢材料的研究现状,涉及本征二硫化钼物性调节策略以及原子掺杂的表面工程和界面工程调制,阐明了相应的催化增强机制,揭示了制备全pH范围兼具活性和高电流稳定性的催化剂是电催化材料的发展趋势,并提出激活多级结构二硫化钼材料惰性基面、提高材料整体导电性、精准锚定单原子以及包覆多孔碳是设计高效全pH催化剂的根本策略。     

Metal-organic frameworks derived FeS2@CoS2 heterostructure for efficient and stable bifunctional electrocatalytic water splitting

The exploration of efficient metal-based bifunctional catalysts for electrochemical water splitting is a promising approach for large-scale applications. In this work, we constructed a FeS₂@CoS₂ heterostructure electrocatalyst by a facile solution-dipping and hydrothermal method. The optimum FeS₂@CoS₂ heterostructure showed notable oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performances, with overpotential values of 280 mV and 136 mV (10 mA cm⁻² current density), respectively. Additionally, the electrocatalyst exhibited a robust stability performance of 50 h at a current density of 10 mA cm⁻². The two-cell electrolyzer is assembled using FeS₂@CoS₂||FeS₂@CoS₂ and delivers a cell voltage of 1.62 V and 1.99 V at 10 and 50 mA cm⁻² current densities with excellent durability. The outstanding overall water-splitting activity of the obtained heterostructure can be attributed to effective electronic interactions, synergistic effects, and exposure of more reactive active sites in the electrocatalyst. This work presents a promising strategy for developing highly active and cost-effective metal sulfide-based bifunctional electrocatalysts for energy conversion technology.     

电解海水催化剂的设计与改性

电解海水是一种可再生、可持续、低成本且节约淡水资源的氢气生产方案。因此,针对天然海水或盐水电解质的析氢反应（HER）和析氧反应（OER）,设计开发高效、稳定的电催化剂具有良好的应用前景。为了深入了解海水电解所面临的现状和挑战,本文对电催化分解海水催化剂的设计思路与改性方法进行了系统的回顾和总结。首先详细讨论了电解海水中析氢反应、析氧反应、析氯反应的基本原理。随后对最近报道的在海水中能够稳定运行的HER和OER电催化剂进行了汇总和分析。针对阴极催化剂,分别概述了高效贵金属基电催化剂和低成本过渡金属基电催化剂。针对阳极催化剂,主要讨论了取得较大进展的镍基催化剂,随后对镍基之外的其他电催化剂进行对比补充。文章最后对电解海水催化剂目前所面临的挑战和发展方向进行了总结和展望,基于现有分析认为,在未来的研究中需要进一步探索新型电解海水催化剂的种类和结构,开发更高效稳定的阴极和具有更高OER选择性的阳极电催化剂,以满足分解海水电催化剂工业化应用的要求。     

Hierarchical CoP3/NiMoO4 heterostructures on Ni foam as an efficient bifunctional electrocatalyst for overall water splitting

Controllable synthesis strategies of the cost-effective and high-active non-noble metal bifunctional electrocatalysts for overall water splitting are imperatively required. Herein, the hierarchical heterostructure CoP₃/NiMoO₄ nanosheets on Ni foam (CoP₃/NiMoO₄–NF) are synthesized by hydrothermal, annealing and phosphorization treatment. The synergistic effect between CoP₃ and NiMoO₄ remarkably promotes the HER intrinsic activity. Moreover, the Ni foam promotes the vertical growth of well-aligned nanosheet arrays, which expose more active sites for HER and OER. The CoP₃/NiMoO₄–NF-2 (Co/Mo = 1/1) electrocatalyst reveals a low overpotential of 92 mV for HER and 347 mV for OER at 10 mA cm⁻² in 1.0 M KOH. Especially, the CoP₃/NiMoO₄–NF-2 exhibits exceptional performance for overall water splitting which presents a low cell voltage of 1.57 V at 10 mA cm⁻², and outstanding durability which could maintain over 12 h. The design strategy and controllable synthesis of the hierarchical heterostructure bifunctional electrocatalyst will be beneficial for efficient overall water splitting.     

Electrocatalysis by design: Effect of the loading level of Au nanoparticles-MnOx nanoparticles binary catalysts on the electrochemical reduction of molecular oxygen

This study concerns the efficient electrochemical reduction of molecular oxygen (O₂), in O₂-saturated 0.1 M KOH solution, to OH⁻ through a four-electron reduction pathway by a novel binary catalyst that is comprised of two kinds of catalysts, i.e., Au nanoparticles (nano-Au) and manganese oxide nanoparticles (nano-MnOx) electrodeposited onto a relatively inert substrate, e.g., glassy carbon (GC) electrode. The nano-Au catalyst is efficiently used for the electro-reduction of O₂ to hydrogen peroxide through a two-electron reduction pathway at a reasonably low overpotential. While the latter (i.e., nano-MnOx) is effectively used for the subsequent catalytic decomposition of the electrogenerated hydrogen peroxide to water and molecular oxygen. The dependence of the electrocatalytic activity of the proposed binary catalysts towards the oxygen reduction on the loading level of both species has been investigated in this paper. This is done aiming at the preparation of a binary catalyst composed of the optimum amounts of both species which supports an apparent four-electron reduction of O₂ at sufficiently low overpotential in replacement of the costly Pt-based electrocatalysts.     

Perspective of hydrogen energy and recent progress in electrocatalytic water splitting

As a secondary energy with great commercialization potential, hydrogen energy has been widely studied due to the high calorific value, clean combustion products and various reduction methods. At present, the blueprint of hydrogen energy economy in the world is gradually taking shape. Compared with the traditional high-energy consuming methane steam reforming hydrogen production method, the electrocatalytic water splitting hydrogen production stands out among other process of hydrogen production owning to the mild reaction conditions, high-purity hydrogen generation and sustainable production process. Basing on current technical economy situation, the highly electric power cost limits the further promotion of electrocatalytic water splitting hydrogen production process. Consequently, the rational design and development of low overpotential and high stability electrocatalytic water splitting catalysts are critical toward the realization of low-cost hydrogen production technology. In this review, we summarize the existing hydrogen production methods, elaborate the reaction mechanism of the electrocatalytic water splitting reaction under acidic and alkaline conditions and the recent progress of the respective catalysts for the two half-reactions. The structure–activity relationship of the catalyst was deep-going discussed, together with the prospects of electrocatalytic water splitting and the current challenges, aiming at provide insights for electrocatalytic water splitting catalyst development and its industrial applications.     

Tunable Ni/Fe-Mo carbide catalyst with high activity toward hydrogen evolution reaction

Cost-effective catalysts for hydrogen evolution reaction (HER) are attractive for sustainable production of H₂ fuel. Herein, a series of tunable Ni/Fe-Mo carbide catalysts have been synthesized via a sol-gel method coupling with a subsequent high temperature carbonization process. The amount of nickel and iron was tuned in the Mo₇/C precursors, accomplishing a favourable performance of noble-metal-free electrocatalysts for HER. As expected, the designed Ni₁₀Fe₄Mo₇/C catalyst displays an enhanced catalytic activity toward hydrogen production with an ultralow overpotential (η₁₀ = 110 mV) and striking kinetics (η_onset = 58 mV, k = 54 mV · dec⁻¹) in the alkaline electrolyte (1 M KOH), which are comparable to those of the commercial 20% Pt/C catalyst. Such excellent performance of Ni₁₀Fe₄Mo₇/C could be attributed to the high intrinsic activities of Ni-based alloys (NiMo₄) and Mo₂C, as well as to the lattice contraction in the Mo₂C unit cell, in accordance with its high electrochemical surface area (~133 m² · g⁻¹) and low charge-transfer resistance (~31.5 Ω) for the associated electrode.     

P-doped MoS2/Ni2P/Ti3C2Tx heterostructures for efficient hydrogen evolution reaction in alkaline media

By combining the advantages of doping to change the electronic structure of molybdenum disulfide (MoS₂), transition metal phosphides, and MXene, we proposed the idea of designing and preparing a new type of composite material, P-doped MoS₂/Ni₂P/Ti₃C₂T_x heterostructures (denoted as P@MNTC), to serve as the hydrogen evolution reaction (HER) catalyst of electrochemical water splitting. The as-prepared P@MNTC heterostructures show a significant HER activity with an overpotential of 120 mV at 10 mA cm^–2 in alkaline electrolyte, with decreasing 105 and 125 mV compared with those of MoS₂ and MXene, respectively. The density functional theory indicates that the P doping and synergy effect of Ti₃C₂T_x can enhance the activation of MoS₂ and thus promote dissociation and absorption of H₂O during HER process. This strategy provides a promising way to develop high-efficiency MoS₂- and Ti₃C₂T_x-based composite catalysts for alkaline HER.     

Metal-organic framework-derived Ni doped Co3S4 hierarchical nanosheets as a monolithic electrocatalyst for highly efficient hydrogen evolution reaction in alkaline solution

Hierarchical nanostructure construction and electronic structure engineering are commonly employed to increase the electrocatalytic activity of HER electrocatalysts. Herein, Ni doped Co₃S₄ hierarchical nanosheets on Ti mesh (Ni doped Co₃S₄ HNS/TM) were successfully prepared by using metal organic framework (MOF) as precursor which was synthesized under ambient condition. Characterization results confirmed this structure and Ni incorporation into Co₃S₄ lattice as well as the modified electronic structure of Co₃S₄ by Ni doping. Alkaline HER performance showed that Ni doped Co₃S₄ HNS/TM presented outstanding HER activity with 173 mV overpotential at -10 mA·cm^-2, surpassing most of metal sulfide-based electrocatalysts. The hierarchical structure, superior electrical conductivity and electronic structure modulation contributed to the accelerated water dissociation and enhanced intrinsic activity. This work provides a new avenue for synthesizing hierarchical nanostructure and simultaneously tuning the electronic structure to promote HER performance, which has potential application in designing highly efficient and cost-effective HER nanostructured electrocatalyst.     

Platinum-coated nanostructured oxides for active catalytic electrodes

In this work we propose the use of platinum-coated nanostructured oxides for improving the redox rate of active electrodes for applications in catalysts for water splitting, fuel cells, organic depollution, etc. In order to test this concept, CaCu₃Ti₄O₁₂ nanorods were grown by magnetron sputtering over Si/SiO₂/Ti/Pt substrates and coated with a platinum layer using the same technique. The performance of this active electrode was studied by cyclic voltammetry and electrochemical impedance spectroscopy. Other Pt films (both dense and porous) deposited on oxidized silicon, and platinum-coated FTO-glass, when tested under the same conditions, were less efficient. The charge transfer resistance and the capacitance of one dimensional platinum-coated nanostructured electrodes were at least one order of magnitude better than those measured for platinum-coated FTO-glass.     

临界点干燥仪制备的Pt-P25的电催化析氢反应性能探究

在各种制氢工艺中,电解水是一种获得氢能源的重要途径,Pt是析氢反应(HER)中最理想的催化剂。由于Pt基材料的稀缺性和高成本限制了其大规模应用,因此迫切需要开发一种低含量、高效的铂催化剂。P25是一种晶格缺陷密度很高的混晶型TiO₂,载流子浓度大,具有良好的催化效果。本文采用临界点干燥仪,以商业化混晶TiO₂(P25)为基底,制备了Pt负载的TiO₂(Pt-P25)催化剂,运用XRD、TEM和XPS分析了催化剂的结构和形貌,探索了不同临界点干燥条件下Pt-P25的电催化HER性能。结果表明,临界点干燥法成功制备出了Pt原子簇负载的TiO₂,且在一定的条件下,当二氧化碳进气速率为慢速、交换速率为7、出气加热速率为中速时,Pt-P25的电催化HER性能最好。     

钌基碱性电解水制氢催化剂研究进展

碱性电解水具有操作易实现、设备费用低和寿命长的特点,是目前应用最广泛的将可再生资源转化为氢能的技术。但电解水存在能耗高的问题,因此需要高效催化剂提高能量转化效率。钌具有与铂相近的金属-氢键强度,是极具前景的制氢催化剂。综述了近年来钌基催化剂的制备及其碱性电解水制氢反应的最新研究进展。与廉价过渡金属材料相比,钌基催化剂具有优异的电化学活性和稳定性,是一种很有前景的析氢材料。以目前主要研究的钌金属及其合金、钌基磷化物、钌基硫化物、钌基硒化物为代表,分别进行了简要的介绍和评价,最后提出了钌基电催化剂在制氢应用中存在的问题和未来的发展方向。     

Structural engineering of transition metal-based nanostructured electrocatalysts for efficient water splitting

Water splitting is a highly promising approach for the generation of sustainable, clean hydrogen energy. Tremendous efforts have been devoted to exploring highly efficient and abundant metal oxide electrocatalysts for oxygen evolution and hydrogen evolution reactions to lower the energy consumption in water splitting. In this review, we summarize the recent advances on the development of metal oxide electrocatalysts with special emphasis on the structural engineering of nanostructures from particle size, composition, crystalline facet, hybrid structure as well as the conductive supports. The special strategies relay on the transformation from the metal organic framework and ion exchange reactions for the preparation of novel metal oxide nanostructures with boosting the catalytic activities are also discussed. The fascinating methods would pave the way for rational design of advanced electrocatalysts for efficient water splitting.