Toward practical artificial photosynthesis: Engineering photocatalytic systems for efficient and scalable solar fuel production

Abstract

Sunlight is our largest energy resource, but it is diffuse and intermittent. Artificial photosynthesis aims to capture and store it in the chemical bonds of fuels. Among the possible approaches, photocatalysts built from light-absorbing semiconductors suspended in water are especially appealing for the simple system design and potential low cost, yet their practical use is still limited by low efficiency and the absence of scalable device architectures. This Account describes how our group has worked on these problems, by designing efficient visible-light-absorbing materials, improving charge utilization and rethinking the overall reaction system. We first designed visible-light-responsive photocatalysts, where cation doping and heteroanion substitution tune band and crystal structures in concert to broaden light absorption. An alternative route is to combine two photocatalysts in a Z-scheme system, mimicking the two-stage light reactions of natural photosynthesis. A key difficulty here is efficient electron transfer between the two photocatalysts. To address this, we developed scalable photocatalyst sheets in which a conductive layer mediates interparticle electron transport, setting a benchmark for photocatalytic water splitting. The same design also converts CO2 into carbon-based fuels when combined with molecular catalysts or living microorganisms. These advances move particulate photocatalysis a step closer to practical solar fuel production.