Gao Taotao, An Qi, Tang Xiangmin, Yue Qu, Zhang Yang, Li Bing, Li Panpan, Jin Zhaoyu
Institute for Advanced Study and School of Mechanical Engineering, Chengdu University, Chengdu, 610106, P. R. China.
Hubei Key Laboratory of Wudang Local Chinese Medicine Research, Hubei University of Medicine, Shiyan, 442000, P. R. China.
Phys Chem Chem Phys. 2024 Jul 24;26(29):19606-19624. doi: 10.1039/d4cp01680g.
Hydrogen energy with its advantages of high calorific value, renewable nature, and zero carbon emissions is considered an ideal candidate for clean energy in the future. The electrochemical decomposition of water, powered by renewable and clean energy sources, presents a sustainable and environmentally friendly approach to hydrogen production. However, the traditional electrochemical overall water-splitting reaction (OWSR) is limited by the anodic oxygen evolution reaction (OER) with sluggish kinetics. Although important advances have been made in efficient OER catalysts, the theoretical thermodynamic difficulty predetermines the inevitable large potential (1.23 V RHE for the OER) and high energy consumption for the conventional water electrolysis to obtain H. Besides, the generation of reactive oxygen species at high oxidation potentials can lead to equipment degradation and increase maintenance costs. Therefore, to address these challenges, thermodynamically favorable anodic oxidation reactions with lower oxidation potentials than the OER are used to couple with the cathodic hydrogen evolution reaction (HER) to construct new coupling hydrogen production systems. Meanwhile, a series of robust catalysts applied in these new coupled systems are exploited to improve the energy conversion efficiency of hydrogen production. Besides, the electrochemical neutralization energy (ENE) of the asymmetric electrolytes with a pH gradient can further promote the decrease in application voltage and energy consumption for hydrogen production. In this review, we aim to provide an overview of the advancements in electrochemical hydrogen production strategies with low energy consumption, including (1) the traditional electrochemical overall water splitting reaction (OWSR, HER-OER); (2) the small molecule sacrificial agent oxidation reaction (SAOR) and (3) the electrochemical oxidation synthesis reaction (EOSR) coupling with the HER (HER-SAOR, HER-EOSR), respectively; (4) regulating the pH gradient of the cathodic and anodic electrolytes. The operating principle, advantages, and the latest progress of these hydrogen production systems are analyzed in detail. In particular, the recent progress in the catalytic materials applied to these coupled systems and the corresponding catalytic mechanism are further discussed. Furthermore, we also provide a perspective on the potential challenges and future directions to foster advancements in electrocatalytic green sustainable hydrogen production.
氢能具有高热值、可再生和零碳排放等优点，被认为是未来清洁能源的理想选择。由可再生和清洁能源驱动的水电化学分解，为制氢提供了一种可持续且环保的方法。然而，传统的电化学全水分解反应（OWSR）受到阳极析氧反应（OER）动力学迟缓的限制。尽管高效OER催化剂已取得重要进展，但理论热力学难题决定了传统水电解获得氢气时不可避免地存在较大电位（OER为1.23 V RHE）和高能耗。此外，在高氧化电位下产生的活性氧会导致设备降解并增加维护成本。因此，为应对这些挑战，采用氧化电位低于OER的热力学有利阳极氧化反应与阴极析氢反应（HER）耦合，构建新的耦合制氢系统。同时，开发了一系列应用于这些新耦合系统的高效催化剂，以提高制氢的能量转换效率。此外，具有pH梯度的不对称电解质的电化学中和能（ENE）可进一步促进制氢应用电压和能耗的降低。在本综述中，我们旨在概述低能耗电化学制氢策略的进展，包括（1）传统的电化学全水分解反应（OWSR，HER - OER）；（2）小分子牺牲剂氧化反应（SAOR）和（3）分别与HER耦合的电化学氧化合成反应（EOSR）（HER - SAOR，HER - EOSR）；（4）调节阴极和阳极电解质的pH梯度。详细分析了这些制氢系统的工作原理、优点和最新进展。特别地，进一步讨论了应用于这些耦合系统的催化材料的最新进展及相应的催化机理。此外，我们还对电催化绿色可持续制氢未来发展中潜在的挑战和方向提出了展望。
