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The development of renewable and affordable energy is crucial for building a sustainable society. In this context, establishing a sustainable infrastructure for renewable energy requires the integration of energy storage, specifically use of renewable hydrogen. The hydrogen evolution reaction (HER) of electrochemical water splitting is a promising method for producing green hydrogen. Recently, two-dimensional nanomaterials have shown great promise in promoting the HER in terms of both fundamental research and practical applications due to their high specific surface areas and tunable electronic properties. Among them, molybdenum disulfide (MoS2), a non-noble metal catalyst, has emerged as a promising alternative to replace expensive platinum-based catalysts for the HER because MoS2 has a high inherent activity, low cost, and abundant reserves. At present, greatly improved activity and stability are urgently needed for MoS2 to enable wide deployment of water electrolysis devices. In this regard, efficient strategies for precisely modifying MoS2 are of interest. Herein, the progress made with MoS2 as an HER catalyst is reviewed, with a focus on modification strategies, including phase engineering, morphology design, defect engineering, heteroatom doping, and heterostructure construction. It is believed that these strategies will be helpful in designing and developing high-performance and low-cost MoS2-based catalysts by lowering the charge transfer barrier, increasing the active site density, and optimizing the surface hydrophilicity. In addition, the challenges of MoS2 electrocatalysts and perspectives for future research and development of these catalysts are discussed.

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Hydrogen, especially the green hydrogen based on water electrolysis, is of great importance to build a sustainable society due to its high-energy-density, zero-carbon-emission features, and wide-range applications. Today's water electrolysis is usually carried out in either low-temperature (<100 degrees C), e.g., alkaline electrolyzer, or high-temperature (>700 degrees C) applications, e.g., solid oxide electrolyzer. However, the low-temperature devices usually suffer from high applied voltages (usually >1.5 V @0.01 A cm(-2)) and high cost; meanwhile, the high-temperature ones have an unsatisfied lifetime partially due to the incompatibility among components. Reasonably, an intermediate-temperature device, namely, proton ceramic cell (PCC), has been recently proposed. The widely-used air electrode for PCC is based on double O2-/e(-) conductor or composited O2-/e(-) -H+ conductor, limiting the accessible reaction region. Herein, we designed a single-phase La0.8Sr0.2Co1-xMnxO3-delta (LSCM) with triple H+/O2-/e(-) conductivity as the air electrode for PCCs. Specifically, the La0.8Sr0.2Co0.8Mn0.2O3-delta (LSCM8282) incorporates 5.8% proton carriers in molar fraction at 400 degrees C, indicating superior proton conducting ability. Impressively, a high current density of 1580 mA cm(-2) for hydrogen production (water electrolysis) is achieved at 1.3 V and 650 degrees C, surpassing most low- and high-temperature devices reported so far. Meanwhile, such a PCC can also be operated under a reversible fuel cell mode, with a peak power density of 521 mW cm(-2) at 650 degrees C. By correlating the electrochemical performances with the hydrated proton concentration of single-phase triple conducting air electrodes in this work and our previous work, a principle for rational design of high-performance PCCs is proposed. (C) 2022 The Chinese Ceramic Society. Production and hosting by Elsevier B.V.

Hydrogen, especially the green hydrogen based on water electrolysis, is of great importance to build a sustainable society due to its high-energy-density, zero-carbon-emission features, and wide-range applications. Today's water electrolysis is usually carried out in either low-temperature (<100 degrees C), e.g., alkaline electrolyzer, or high-temperature (>700 degrees C) applications, e.g., solid oxide electrolyzer. However, the low-temperature devices usually suffer from high applied voltages (usually >1.5 V @0.01 A cm(-2)) and high cost; meanwhile, the high-temperature ones have an unsatisfied lifetime partially due to the incompatibility among components. Reasonably, an intermediate-temperature device, namely, proton ceramic cell (PCC), has been recently proposed. The widely-used air electrode for PCC is based on double O2-/e(-) conductor or composited O2-/e(-) -H+ conductor, limiting the accessible reaction region. Herein, we designed a single-phase La0.8Sr0.2Co1-xMnxO3-delta (LSCM) with triple H+/O2-/e(-) conductivity as the air electrode for PCCs. Specifically, the La0.8Sr0.2Co0.8Mn0.2O3-delta (LSCM8282) incorporates 5.8% proton carriers in molar fraction at 400 degrees C, indicating superior proton conducting ability. Impressively, a high current density of 1580 mA cm(-2) for hydrogen production (water electrolysis) is achieved at 1.3 V and 650 degrees C, surpassing most low- and high-temperature devices reported so far. Meanwhile, such a PCC can also be operated under a reversible fuel cell mode, with a peak power density of 521 mW cm(-2) at 650 degrees C. By correlating the electrochemical performances with the hydrated proton concentration of single-phase triple conducting air electrodes in this work and our previous work, a principle for rational design of high-performance PCCs is proposed. (C) 2022 The Chinese Ceramic Society. Production and hosting by Elsevier B.V.

Hydrogen, especially the green hydrogen based on water electrolysis, is of great importance to build a sustainable society due to its high-energy-density, zero-carbon-emission features, and wide-range applications. Today's water electrolysis is usually carried out in either low-temperature (<100 degrees C), e.g., alkaline electrolyzer, or high-temperature (>700 degrees C) applications, e.g., solid oxide electrolyzer. However, the low-temperature devices usually suffer from high applied voltages (usually >1.5 V @0.01 A cm(-2)) and high cost; meanwhile, the high-temperature ones have an unsatisfied lifetime partially due to the incompatibility among components. Reasonably, an intermediate-temperature device, namely, proton ceramic cell (PCC), has been recently proposed. The widely-used air electrode for PCC is based on double O2-/e(-) conductor or composited O2-/e(-) -H+ conductor, limiting the accessible reaction region. Herein, we designed a single-phase La0.8Sr0.2Co1-xMnxO3-delta (LSCM) with triple H+/O2-/e(-) conductivity as the air electrode for PCCs. Specifically, the La0.8Sr0.2Co0.8Mn0.2O3-delta (LSCM8282) incorporates 5.8% proton carriers in molar fraction at 400 degrees C, indicating superior proton conducting ability. Impressively, a high current density of 1580 mA cm(-2) for hydrogen production (water electrolysis) is achieved at 1.3 V and 650 degrees C, surpassing most low- and high-temperature devices reported so far. Meanwhile, such a PCC can also be operated under a reversible fuel cell mode, with a peak power density of 521 mW cm(-2) at 650 degrees C. By correlating the electrochemical performances with the hydrated proton concentration of single-phase triple conducting air electrodes in this work and our previous work, a principle for rational design of high-performance PCCs is proposed. (C) 2022 The Chinese Ceramic Society. Production and hosting by Elsevier B.V.