Published as part of Chemical Reviews special issue “Green Hydrogen”. Green hydrogen, produced through water electrolysis powered by renewable energy, is an essential component of future global energy systems. In this thematic issue of Chemical Reviews, we present a collection of reviews on some of the key research topics related to the design of components and understanding of the elementary processes in current and emerging water-electrolysis technologies. Green hydrogen is produced through water electrolysis powered by renewable energy sources, such as wind, solar, or hydropower, or possibly nuclear energy, resulting in low carbon emissions. (1) While the CO₂ equivalent per kilogram of hydrogen produced (kgCO₂e/kgH₂) depends on many factors and requires a lifecycle analysis to assess, the U.S. Department of Energy’s Section 45 V tax credit targets green hydrogen at below 0.45 kgCO₂e/kgH₂. (2) This requires minimizing emissions throughout the entire production process, including electricity use and upstream activities. These emissions are much lower than “gray” hydrogen from reforming natural gas (CH₄ + 2H₂O → CO₂ + 4H₂) with ∼10 kgCO₂e/kgH₂ and “blue” hydrogen using natural gas with carbon capture and ∼4 kgCO₂e/kgH₂. (3) Green hydrogen can dramatically reduce carbon-dioxide emissions associated with transportation and heavy industry. In transportation, hydrogen will be used where direct electrification is challenging, for example in aviation, shipping, and trucking. How the hydrogen is used will depend on the scale and cost of the (currently expensive) infrastructure to store and transport hydrogen. Pipelines are in principle cost-effective, but retrofitting existing natural-gas infrastructure is difficult (in part due to metals embrittlement discussed in this issue (4)). Hydrogen can also be combined with captured CO₂ in efficient thermochemical processes to produce hydrocarbons, such as methanol or synthetic aviation fuels. (5) These renewable fuels can displace conventional fossil fuels without requiring major infrastructure changes, but CO₂ capture (not discussed here) is an issue. (6) Hydrogen is also essential for the production and upgrading of biofuels, particularly synthetic fuels derived from renewable biomass. Substantial amounts of hydrogen─roughly ¹/₂H₂ per carbon atom─in the resulting fuel are used to remove heteroatoms via hydro-deoxygenation, hydro-desulfurization, and hydro-denitrogenation processes. (7) Green hydrogen is likely to serve important roles in the future fully renewable electric grid that must deal with intermittent wind and solar generation on the daily, seasonal, and decadal time scales. (8,9) When energy storage is needed to fill gaps in production over multiple days, electricity generation from fuel cells and stored hydrogen become economically compelling, especially as the costs of fuel cells and electrolyzers continue to rapidly decline. (10) The ability of green hydrogen electrolyzers to serve as dispatchable load will also play a large role in enabling a reliable, expanded, and fully renewable electric grid. When renewable energy production is high or demand low, electrolyzers ramp up to productively use surplus electricity, and during peak demand, electrolyzers turn down or off. The hydrogen produced from these intermittent electrolyzers will be buffered in storage facilities and piped for industrial uses in fertilizer synthesis via Haber–Bosch chemistry and future green-steel and synthetic fuels industries. Fertilizer synthesis alone accounts for 2% of global CO₂ emissions─most of which come from making the fossil hydrogen currently used (and thus readily displaced by green hydrogen). This also enables seasonal energy storage to ensure grid reliability and obviate the need for natural-gas peaker plants. Electric power markets will evolve to create profitable businesses around this range of grid services. Despite these advantages for green-hydrogen production, there remain many technical and scaling challenges. The U.S. DOE has established the Hydrogen Earthshot goal to reduce the cost of producing green hydrogen to $1 per kg by 2030, roughly an 80% reduction from the current ∼$5/kg. Storing and transporting hydrogen add more challenges that increase costs, as hydrogen gas has a low energy density compared to liquid hydrocarbons. Liquefaction of hydrogen requires energy-intensive processes. New infrastructure, including high-pressure tanks, possible cryogenic systems, and pipelines resistant to hydrogen embrittlement are needed. Transportation costs are historically expensive due to limited capacity, safety protocols, and energy losses from evaporation. There are a number of realistic pathways to reach the $1 per kg hydrogen target, bolstered by the science and technology innovation discussed in this thematic issue, coupled with reduced production costs with scaling. (11) A basic calculation is simple. The thermoneutral voltage for liquid water electrolysis is 1.48 V; below this voltage requires extra heat input. Faraday’s law (and unit conversion) yields a minimum of 39.4 kW·h per kg of hydrogen. A modern electrolyzer runs between 1.7 and 2.0 V, depending on current density, and there is additional electrical power associated with balance of plant. A practical high-performance electrolyzer thus requires ∼50 kW·h per kg H₂. Therefore, electricity is needed at $0.01–$0.015 per kW·h so that the electricity cost is $0.50–$0.75 per kg H₂. This need for extremely low-cost electrical energy has been used to argue that the cost target is not possible, particularly by entities involved in competing energy technologies. Yet the economics of the electric grid is changing. In 2024 there were a record number of hours with negative electricity prices in the European, Texas, and California markets where intermittent renewable generation has high penetration. While markets will adapt to limit negative electric prices, renewables will be overbuilt to provide capacity when rates are high─this necessarily leads to periods when rates are low. The fraction of time for which rates will average $0.01 per kW·h is unknown but is likely to be substantial. A reasonable prediction is that electrolyzer systems can run with 30% capacity factor and access ∼$0.01 per kW·h electricity, i.e. during the middle of the day and/or when there is high wind. While current electrolyzer prices from US and European manufacturers are too high to run at 30% capacity factor (∼1000 $/kW combined price for alkaline stacks and balance of plant), (12) electrolyzer prices are dropping with manufacturing scale; similar, although a bit slower, to how battery and photovoltaic technologies have, (13) which both dropped ∼10× since 2010. If we then assume a reasonable capital cost of $200 per kW by 2030, and a 20-year lifetime running at 30% capacity factor, the amortized cost is $0.19 per kg of H₂. While there are additional maintenance, land, and financing costs, the sum of electric and equipment expenses can be below $1 per kg of hydrogen over a range of scenarios. The above simple analysis makes the case that the core needs for electrolysis are that next-generation technologies: be relatively inexpensive and thus not use large amounts of precious metals (although low loadings may be acceptable), have electrode, catalyst, and system designs that allow for intermittent operation without damage to the cell, be able to operate with high efficiency given the high fraction of the cost electrical energy is to the output hydrogen, even at ∼$0.01 per kW·h, and must be durable for at least a decade or two under these conditions (recognizing that electrode/stack reconditioning may be much less expensive than building entirely new systems and enable operation for much longer). The contributions in this thematic issue of Chemical Reviews reflect the interdisciplinary nature of the science and engineering research needed to overcome the challenges associated with green hydrogen and reach the cost levels where hydrogen is able to dramatically reduce carbon dioxide emissions from large segments of the global economy. Several of the reviews deal with solid-oxide-based electrochemical technology. For example, Ming Chen’s review provides analysis of solid oxide electrolysis cells (SOECs), which offer the highest efficiency (∼36 kWh/kg) among all technologies because they operate at temperatures near 800 °C, where thermodynamics favor efficient water splitting and the electrode kinetics are fast. (14) The review covers advances in SOEC component design─from electrodes to electrolytes─and discusses strategies for mitigating performance degradation over time, which is a major issue today with this technology. Challenges, such as stack scalability, cost, and system durability, are addressed, with recommendations for future research focused on enhancing reliability and reducing capital costs. Eranda Nikolla’s review focuses on solid-oxide cells (SOCs), particularly those that can switch between fuel-cell and electrolyzer modes. (15) SOCs are relevant in the context of green hydrogen because they can efficiently convert renewable electricity into hydrogen during times of surplus and generate power from hydrogen when energy demand peaks, both with much higher thermodynamic efficiency than possible in lower temperature (<100 °C) systems. The review highlights significant degradation of electrocatalytic materials under dynamic conditions, such as switching between modes or handling multiple fuel types, and identifies the bottlenecks in catalytic performance due to effects such as sintering, poisoning, and undergoing phase transitions, and provides guidelines for designing stable, efficient electrode catalysts. Other reviews discuss materials and processes for low temperature electrolysis systems that rely on liquid water and either alkaline or acidic electrolytes. Paul Kempler’s review focuses on the role of gas bubbles generated during the hydrogen and oxygen evolution reactions in electrolysis. (16) Gas evolution impacts the overall efficiency of electrolyzers by blocking active catalytic sites, increasing electrical resistance, and disrupting fluid dynamics at the electrode surface. The review discusses techniques for characterizing gas evolution in real time and optimizing electrode designs to enhance gas removal at high current densities. Effective bubble management is particularly essential for liquid alkaline electrolysis technology that has been historically limited to lower current densities (<0.5 A cm^–2) and constant current operation, but where innovation could enable dynamic operation and higher currents (∼1–2 A cm^–2) at high efficiency. The review identifies key strategies, such as tailoring electrode surfaces and structure to promote gas transport and bubble detachment. Managing gas evolution directly impacts the operational efficiency of electrolyzers, particularly at the high currents needed to reduce capital expense. Dirk Henkensmeier’s review focuses on another key component for alkaline water electrolysis─the separator and/or membrane between the anode and cathode. (17) The review traces the historical evolution from asbestos-based diaphragms to polymeric composite diaphragms and the possibility to employ anion exchange membranes (AEMs), which offer improved conductivity and safety but are not yet fully proven stable for commercial application. Challenges in balancing the trade-offs between conductivity, membrane lifetime, and operational costs are discussed highlighting recent developments in ion-solvating membranes and improvements in AEM durability in strong hot alkaline solutions through chemical structure design. Thinner separators with lower ionic resistance that can effectively separate the evolved hydrogen and oxygen under varying load are central to lower the capital cost of the liquid alkaline electrolysis through higher current density while maintaining high efficiency. Travis Jones’s review provides a detailed review of oxygen evolution reaction (OER) catalysts and their fundamental mechanisms, focusing on the challenges involved in understanding and modeling multiple electron transfers and bond-forming/breaking steps. (18) The review traces the evolution of OER models, from early phenomenological approaches to modern ab initio simulations that incorporate electric fields, solvent effects, and explicit reaction kinetics. Jones explores how these models compare with experiment and identifies areas where key work is needed to bridge theory and practice. Because the OER is one of the major sources of inefficiency in low-temperature water-electrolysis technology, these understandings are central to designing electrodes with better activity and durability without resorting to high mass loading of expensive precious metals (in the case of proton-exchange membrane, PEM, electrolysis technology). Laurie King’s review addresses an important challenge facing PEM electrolysis technology, the use of precious metals. (19) PEM electrolyzers offer perhaps the most-compelling performance metrics, but remain more expensive. Emerging alkaline membrane electrolyzer systems also tend to use precious metal cathodes. (20) The review highlights alternative catalyst materials, including molybdenum disulfides (MoS₂), nickel–molybdenum alloys, phosphides, and carbides, with a focus on their stability and performance in both acidic and alkaline electrolytes, reducing dependence on expensive precious metals, such as platinum, used in hydrogen evolution reaction catalysts. King also evaluates metrics for measuring HER activity and stability, offering insights into best practices for catalyst testing under real-world conditions. Jeffrey Dick’s review focuses on single-entity electrocatalysis, an emerging field that investigates the catalytic behavior of individual nanoparticles, atomic structures, or molecules. (21) Traditional studies measure the performance of catalysts as ensembles, where the activity of many particles is averaged. Dick’s review highlights the experimental challenges of studying single entities, such as the development of new measurement tools and techniques capable of probing individual particles in real-time. Case studies discussed in the review include hydrogen evolution, carbon-dioxide reduction, and hydrazine oxidation, each demonstrating how single-entity studies can uncover new insights into catalyst behavior that ensemble measurements cannot capture. This approach is useful in future catalyst design and targeted improvements in the catalyst nanopowders and nanostructures used in electrolyzer electrodes. Returning to foundational understanding, Yuanyue Liu’s review explores the potential of atomistic modeling to accelerate the discovery of high-performance catalysts for green hydrogen production. (22) This review focuses on addressing the complexity of electrochemical interfaces, which involve interactions between dynamic catalysts, electrolyte ions, solvent molecules and electrode surfaces. Liu discusses techniques to model solvation effects, electrode potentials, reaction kinetics, and pH. The review also highlights computational spectroscopy methods, which can bridge the gap between theory and experiment by offering molecular-level insights into mechanisms. Aliaksandr Bandarenka’s review provides an in-depth review of the electrical double layer (EDL)─the critical region of molecular dimensions that forms at the interface between the electrode and the electrolyte, where ions accumulate, large electric fields exist, and solvent and other molecular species have properties very different than those of their bulk counterparts. (23) The review explores experimental techniques and theoretical models used to assess double-layer capacitance and ion interactions at electrochemical interfaces. Bandarenka emphasizes the influence of electrode composition, electrolyte chemistry, temperature, and pressure on EDL behavior, providing insights for optimizing catalysts and improving the efficiency and durability of electrochemical systems. Finally, Haiyang Yu and Zhiliang Zhang’s review addresses perhaps one of the most critical issues for green hydrogen systems: hydrogen embrittlement, a phenomenon in which hydrogen atoms penetrate metallic structures, degrading their mechanical strength and causing cracks or fractures under stress. (4) This degradation is particularly dangerous for pipelines, tanks, and equipment used in hydrogen transport, storage, and processing. With green hydrogen production expected to scale rapidly, hydrogen embrittlement poses a significant threat to infrastructure reliability and safety particularly for any repurposed infrastructure from the natural gas industry. The review discusses how hydrogen interacts with different metals─steels, nickel alloys, and aluminum alloys─commonly used in energy infrastructure. Yu and Zhang explore the behavior of high-entropy alloys, the use of additive manufacturing to produce materials resistant to embrittlement, and the need for AI-driven predictive models to assess material performance and forecast failures. Reliable and predictable materials are central to hydrogen pipelines and storage facilities deployment at scale. The reviews presented in this thematic issue of Chemical Reviews collectively address some of the key science and engineering challenges associated with green-hydrogen production. From fundamental research on catalysts and materials to applied studies on electrolysis systems and gas-evolution, these contributions reflect some, but certainly not all, of the breadth of innovation required to realize the potential of green hydrogen. With work, green hydrogen is poised to be a cornerstone in the global energy transition. Shannon W. Boettcher is the Vermeulen Professor in the Departments of Chemical and Biomolecular Engineering and Chemistry at the University of California, Berkeley, and the Deputy Director of the Energy Storage and Distributed Resources Division at Lawrence Berkeley National Laboratory. From 2010–2023, he was a Professor of Chemistry at the University of Oregon, where he founded the Oregon Center for Electrochemistry and, along with Paul Kempler, the Nation’s first master’s program in Electrochemical Technology. His research includes mechanistic studies of interfacial and transport processes in electrochemical systems and applying the insights in the design of next-generation materials, components, and devices for electrochemical technology, including for hydrogen production by water electrolysis. In 2023 he was named the Blavatnik National Award Laureate in Chemistry. This article references 23 other publications. This article has not yet been cited by other publications.

中文翻译：

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绿色氢能简介


作为 Chemical Reviews 特刊“Green Hydrogen”的一部分发布。绿色氢气是通过可再生能源驱动的水电解生产的，是未来全球能源系统的重要组成部分。在本期《化学评论》的主题中，我们介绍了一系列关于与组件设计和理解当前和新兴水电解技术的基本过程相关的关键研究主题的评论。绿色氢气是通过由可再生能源（如风能、太阳能或水能）或可能的核能提供动力的水电解产生的，因此碳排放量低。（1） 虽然每公斤氢气产生的 CO₂ 当量 （kgCO₂e/kgH₂） 取决于许多因素，并且需要生命周期分析来评估，但美国能源部的第 45 V 条税收抵免将绿色氢气的目标设定在低于 0.45 kgCO₂e/kgH₂ 的水平。（2） 这需要最大限度地减少整个生产过程的排放，包括用电和上游活动。这些排放量远低于使用约 10 kgCO₂e/kgH₂ 的重整天然气（CH₄ + 2H₂O → CO₂ + 4H₂）产生的“灰”氢，以及使用碳捕获天然气和 ∼4 kgCO₂e/kgH₂ 的“蓝”氢。（3） 绿色氢气可以显著减少与运输和重工业相关的二氧化碳排放。在运输方面，氢气将用于直接电气化具有挑战性的领域，例如航空、航运和卡车运输。氢气的使用方式将取决于（目前昂贵的）储存和运输氢气的基础设施的规模和成本。 管道原则上具有成本效益，但改造现有的天然气基础设施很困难（部分原因是本期讨论的金属脆化 （4））。氢气还可以在高效的热化学过程中与捕获的 CO₂ 结合，以生产碳氢化合物，例如甲醇或合成航空燃料。（5） 这些可再生燃料可以取代传统的化石燃料，而无需对基础设施进行重大改造，但 CO₂ 捕获（此处不讨论）是一个问题。（6） 氢气对于生物燃料的生产和升级也是必不可少的，尤其是来自可再生生物质的合成燃料。所得燃料中的大量氢（每个碳原子大约 ¹/₂H₂）用于通过加氢脱氧、加氢脱硫和加氢脱氮过程去除杂原子。（7） 绿色氢在未来的完全可再生电网中可能发挥重要作用，该电网必须在每日、季节性和十年时间尺度上处理间歇性风能和太阳能发电。（8,9） 当需要储能来填补多天的生产缺口时，燃料电池发电和储存的氢气在经济上变得极具吸引力，尤其是在燃料电池和电解槽的成本继续迅速下降的情况下。（10） 绿色氢电解槽作为可调度负载的能力也将在实现可靠、可扩展和完全可再生的电网方面发挥重要作用。当可再生能源产量高或需求低时，电解槽会加速以高效使用剩余电力，而在需求高峰期，电解槽会关闭或关闭。 这些间歇性电解槽产生的氢气将在储存设施中缓冲，并通过管道输送到工业用途，通过 Haber-Bosch 化学和未来的绿色钢铁和合成燃料行业用于肥料合成。仅肥料合成就占全球二氧化碳排放量的 2%，其中大部分来自制造目前使用的化石氢（因此很容易被绿色氢取代）。这也使季节性储能成为可能，以确保电网可靠性并消除对天然气调峰发电厂的需求。电力市场将不断发展，围绕这一系列电网服务创造有利可图的业务。尽管绿色氢气生产具有这些优势，但仍然存在许多技术和规模挑战。美国能源部制定了氢能“为地球奋斗”目标，即到 2030 年将生产绿色氢气的成本降低到每公斤 1 美元，比目前的 ∼5 美元/公斤降低约 80%。储存和运输氢气增加了更多挑战，从而增加了成本，因为与液态碳氢化合物相比，氢气的能量密度较低。氢气的液化需要能源密集型工艺。需要新的基础设施，包括高压罐、可能的低温系统和抗氢脆管道。由于容量有限、安全协议和蒸发造成的能量损失，运输成本历来昂贵。有许多现实的途径可以实现每公斤 1 美元的氢目标，这得益于本专题讨论的科技创新，再加上通过扩大生产成本。（11） 基本计算很简单。液态水电解的热中性电压为 1.48 V;低于此电压需要额外的热量输入。 法拉第定律（和单位换算）得出每公斤氢气至少 39.4 kW·h。现代电解槽的运行电压在 1.7 到 2.0 V 之间，具体取决于电流密度，并且还有与电厂辅助设施相关的额外电力。因此，实用的高性能电解槽需要每 kg H₂ ∼50 kW·h。因此，每千瓦时需要 0.01 至 0.015 美元的电力，因此电费为每公斤 H₂ 0.50 至 0.75 美元。这种对成本极低的电能的需求被用来论证成本目标是不可能的，特别是参与竞争能源技术的实体。然而，电网的经济性正在发生变化。2024 年，欧洲、德克萨斯州和加利福尼亚市场的负电价小时数创下历史新高，这些市场的间歇性可再生能源发电渗透率很高。虽然市场会适应限制负电价，但当电价高时，可再生能源将被过度建设以提供容量——这必然会导致电价低的时期。费率平均为每 kW·h 0.01 美元的时间分数尚不清楚，但可能很大。一个合理的预测是，电解槽系统可以以 30% 的容量系数运行，并获得每千瓦时 0.01 美元的电力，即在中午和/或有大风时。虽然美国和欧洲制造商目前提供的电解槽价格太高，无法以 30% 的容量系数运行（碱性电堆和电厂平衡装置的综合价格约为 1000 美元/kW），（12） 电解槽价格随着制造规模的扩大而下降;与电池和光伏技术类似，尽管速度稍慢，（13） 自 2010 年以来均下降了 ∼10×。 如果我们假设到 2030 年，合理的资本成本为每千瓦 200 美元，并且以 30% 的容量系数运行 20 年的使用寿命，则摊余成本为每公斤 H₂ 0.19 美元。虽然有额外的维护、土地和融资成本，但在一系列情况下，电力和设备费用的总和可能低于每公斤氢气 1 美元。上述简单分析表明，电解的核心需求是下一代技术：相对便宜，因此不使用大量贵金属（尽管低负载可能是可以接受的），具有允许间歇运行而不会损坏电池的系统设计，能够高效运行，因为电能的成本很高，是输出氢气， 即使每千瓦时的价格约为 0.01 美元，并且在这些条件下必须至少耐用十年或二十年（认识到电极/电堆修复可能比构建全新的系统便宜得多，并且能够运行更长时间）。本期《化学评论》专题刊物的贡献反映了克服与绿色氢相关的挑战并达到氢能够大幅减少全球经济大部分部门二氧化碳排放的成本水平所需的科学和工程研究的跨学科性质。一些评论涉及基于固体氧化物的电化学技术。 例如，Ming Chen 的评论提供了对固体氧化物电解槽 （SOEC） 的分析，该电解槽在所有技术中具有最高的效率 （∼36 kWh/kg），因为它们在接近 800 °C 的温度下运行，其中热力学有利于高效的水分解并且电极动力学很快。（14） 该综述涵盖了 SOEC 组件设计的进展——从电极到电解质——并讨论了随着时间的推移缓解性能下降的策略，这是当今该技术的一个主要问题。解决了堆栈可扩展性、成本和系统持久性等挑战，并建议未来研究的重点是提高可靠性和降低资本成本。Eranda Nikola 的评论侧重于固体氧化物电池 （SOC），特别是那些可以在燃料电池和电解槽模式之间切换的电池。（15） SOC 在绿色氢的背景下具有相关性，因为它们可以在过剩时有效地将可再生电力转化为氢气，并在能源需求达到峰值时从氢气中发电，两者的热力学效率都比低温 （<100 °C） 系统高得多。该综述强调了电催化材料在动态条件下的显著降解，例如在模式之间切换或处理多种燃料类型，并确定了由于烧结、中毒和发生相变等影响而导致的催化性能瓶颈，并为设计稳定、高效的电极催化剂提供了指南。其他综述讨论了依赖于液态水和碱性或酸性电解质的低温电解系统的材料和工艺。 Paul Kempler 的评论侧重于电解中析氢和析氧反应过程中产生的气泡的作用。（16） 气体逸出通过阻塞活性催化位点、增加电阻和破坏电极表面的流体动力学来影响电解槽的整体效率。本综述讨论了实时表征气体逸出和优化电极设计以增强高电流密度下气体去除的技术。有效的气泡管理对于液态碱性电解技术尤为重要，该技术历来仅限于较低的电流密度 （<0.5 A cm^–2） 和恒流操作，但创新可以实现动态操作和更高的电流 （∼1–2 A cm^–2） 以高效率。本综述确定了关键策略，例如调整电极表面和结构以促进气体传输和气泡分离。管理气体逸出直接影响电解槽的运行效率，尤其是在需要降低资本支出的大电流下。Dirk Henkensmeier 的评论侧重于碱性水电解的另一个关键部件——阳极和阴极之间的隔膜和/或膜。（17） 该综述追溯了从石棉隔膜到聚合物复合隔膜的历史演变以及使用阴离子交换膜 （AEM） 的可能性，该膜具有更高的导电性和安全性，但尚未完全证明其对商业应用的稳定性。 讨论了在电导率、膜寿命和运营成本之间平衡权衡的挑战，重点介绍了离子溶解膜的最新发展，以及通过化学结构设计提高强热碱性溶液中 AEM 的耐久性。具有较低离子电阻的较薄隔膜可以在不同负载下有效分离释放出的氢和氧，这是通过更高的电流密度降低液碱电解的资本成本同时保持高效率的核心。Travis Jones 的综述详细回顾了析氧反应 （OER） 催化剂及其基本机制，重点介绍了理解和模拟多个电子转移和键形成/断裂步骤所涉及的挑战。（18） 该综述追溯了 OER 模型的演变，从早期的现象学方法到结合了电场、溶剂效应和显式反应动力学的现代 ab initio 模拟。Jones 探讨了这些模型与实验的比较，并确定了需要开展关键工作来连接理论和实践的领域。由于 OER 是低温水电解技术效率低下的主要来源之一，因此这些理解对于设计具有更好活性和耐用性的电极至关重要，而无需诉诸昂贵的贵金属的高质量负载（在质子交换膜、PEM、电解技术的情况下）。Laurie King 的评论解决了 PEM 电解技术面临的一个重要挑战，即贵金属的使用。（19） PEM 电解槽可能提供了最引人注目的性能指标，但仍然更昂贵。 新兴的碱性膜电解槽系统也倾向于使用贵金属阴极。（20） 该综述重点介绍了替代催化剂材料，包括二硫化钼 （MoS₂）、镍钼合金、磷化物和碳化物，重点关注它们在酸性和碱性电解质中的稳定性和性能，减少对显氢反应催化剂中使用的铂等昂贵贵金属的依赖。King 还评估了用于测量 HER 活性和稳定性的指标，为在实际条件下进行催化剂测试的最佳实践提供了见解。Jeffrey Dick 的评论侧重于单实体电催化，这是一个新兴领域，研究单个纳米粒子、原子结构或分子的催化行为。（21） 传统研究以集成的形式测量催化剂的性能，其中许多颗粒的活性被平均。Dick 的评论强调了研究单个实体的实验挑战，例如开发能够实时探测单个粒子的新测量工具和技术。综述中讨论的案例研究包括氢析出、二氧化碳还原和肼氧化，每个案例研究都展示了单一实体研究如何揭示集成测量无法捕捉的催化剂行为的新见解。这种方法可用于未来的催化剂设计和电解槽电极中使用的催化剂纳米粉末和纳米结构的针对性改进。回到基本理解，Yuanyue Liu 的评论探讨了原子建模在加速发现用于绿色氢生产的高性能催化剂方面的潜力。 （22） 本综述侧重于解决电化学界面的复杂性，其中涉及动态催化剂、电解质离子、溶剂分子和电极表面之间的相互作用。Liu 讨论了对溶剂化效应、电极电位、反应动力学和 pH 值进行建模的技术。该综述还强调了计算光谱学方法，该方法可以通过提供对机制的分子水平见解来弥合理论和实验之间的差距。Aliaksandr Bandarenka 的评论深入回顾了双电层 （EDL），这是在电极和电解质之间的界面处形成的分子尺寸的关键区域，离子在这里积累，存在大电场，溶剂和其他分子种类的特性与它们的本体对应物非常不同。（23） 综述探讨了用于评估电化学界面处双电层电容和离子相互作用的实验技术和理论模型。Bandarenka 强调了电极成分、电解质化学、温度和压力对 EDL 行为的影响，为优化催化剂和提高电化学系统的效率和耐久性提供了见解。最后，Haiyang Yu 和 Zhiliang Zhang 的综述解决了绿色氢系统最关键的问题之一：氢脆，即氢原子穿透金属结构，降低其机械强度并在应力下导致裂纹或断裂的现象。（4） 这种降解对于用于氢气运输、储存和加工的管道、储罐和设备尤其危险。 随着绿色氢生产预计将迅速扩大规模，氢脆对基础设施的可靠性和安全性构成重大威胁，尤其是对于天然气行业的任何重新利用的基础设施。该综述讨论了氢如何与能源基础设施中常用的不同金属（钢、镍合金和铝合金）相互作用。Yu 和 Zhang 探讨了高熵合金的行为、使用增材制造生产抗脆性材料，以及需要 AI 驱动的预测模型来评估材料性能和预测故障。可靠且可预测的材料是大规模部署氢气管道和储存设施的核心。本期《化学评论》专题中介绍的综述共同解决了与绿色氢生产相关的一些关键科学和工程挑战。从催化剂和材料的基础研究到电解系统和气体逸出的应用研究，这些贡献反映了实现绿色氢能潜力所需的部分（但肯定不是全部）创新广度。通过工作，绿色氢有望成为全球能源转型的基石。Shannon W. Boettcher 是加州大学伯克利分校化学与生物分子工程系和化学系的 Vermeulen 教授，也是劳伦斯伯克利国家实验室储能和分布式资源部的副主任。从 2010 年到 2023 年，他担任俄勒冈大学的化学教授，在那里他创立了俄勒冈电化学中心，并与 Paul Kempler 一起创立了美国第一个电化学技术硕士课程。 他的研究包括电化学系统中界面和传输过程的机理研究，并将这些见解应用于电化学技术的下一代材料、组件和设备的设计，包括通过水电解制氢。2023 年，他被评为布拉瓦尼克化学国家奖得主。本文引用了其他 23 种出版物。本文尚未被其他出版物引用。