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低碳运输、供暖、电网规模的能源储存和二氧化碳捕获/利用方面发挥重要作用。到2050年，英国的氢气需求量将达到143~860太瓦时/年，而目前的生产能力仅为27太瓦时/年。将充足的太阳光转化为氢气是满足这一需求的有吸引力的方法之一。在各种太阳能制氢技术中，光电化学(PEC)水分解技术因其操作灵活、减少了电子-空穴复合以及H2和O2在两个电极上的自然分离而备受关注。从太阳能光伏商业化的历史轨迹来看，提供市场认可的PEC氢气生产的关键将是(1)能够使用更便宜的材料(如硅)和(2)将STF效率大幅提高到至少20%。SOLO旨在通过开发pH差分策略来改变阳极(OER)和阴极(HER)半反应的单个平衡电位，从而降低能量障碍，从而消除PEC水分解系统中1.23 eV的热力学限制。提出了一种新的无膜式光流控平台，以适应pH差的设计，其中酸和碱性电解液将能够共存于单个电池中。在SOLO平台上将展示有前景的低带隙材料，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.