Solar Optofluidics (SOLO): Water Splitting beyond the 1.23 eV Thermodynamic Constraints

可再生氢将在英国未来的能源中发挥重要作用，用于低碳运输，供暖，电网规模的能源储存和二氧化碳捕获/利用。到2050年，英国的氢气需求量将达到143~860 TWh/年，而目前的产能仅为27 TWh/年。利用丰富的太阳光转化为氢气是一种很有吸引力的方法。在各种太阳能制氢技术中，光电化学（PEC）水裂解由于其操作的灵活性、减少的电子-空穴复合以及H2和O2在两个电极中的自然分离而受到广泛关注。从太阳能光伏商业化的历史轨迹中学习，提供市场可接受的PEC制氢的关键是（1）能够使用更便宜的材料（如硅）和（2）将STF效率显著提高到至少20%。SOLO旨在通过开发pH差异策略来改变阳极（OER）和阴极（HER）半反应的各个平衡电位，从而降低能量势垒，从而消除PEC水裂解系统中的1.23 eV热力学约束。提出了一种新型的无膜光流体平台，以适应pH差异设计，其中酸性和碱性电解质将能够共存于单个电池中。SOLO平台将展示有前途的低带隙材料，以实现成本效益和高STF效率。

Renewable hydrogen will play an important role in the UK's energy future for low carbon transport, heating, grid-scale energy storage and CO2 capture/utilisation. The UK's hydrogen demand would reach 143~860 TWh/year by 2050, while the current production capacity is only 27 TWh/year. Conversion of abundant sunlight to produce H2 is one of attractive approach to meet the demand. Among various solar H2 technology, photoelectrochemical (PEC) water splitting has gained much attention due to its operational flexibility, reduced electron-hole recombination and natural separation of H2 and O2 in two electrodes. Learning from the historic trajectory of solar PV commercialisation, the key to deliver market acceptable PEC hydrogen production will be (1) enabling the use of much cheaper materials (such as silicon) and (2) significantly increasing the STF efficiency to at least 20%. SOLO aims to remove the 1.23 eV thermodynamic restraints from the PEC water splitting system, by developing a pH-differential strategy to alter the individual equilibrium potentials of anodic (OER) and cathodic (HER) half reactions, thus reducing the energy barrier. A novel membraneless optofluidic platform is proposed to accommodate the pH-differential design, where acid and alkaline electrolyte will be able to co-exist in a single cell. Promising low bandgap materials will be demonstrated in the SOLO platform to achieve cost effectiveness and high STF efficiency.