Benchmark performance of low-cost Sb2Se3 photocathodes for unassisted solar overall water splitting
Wooseok Yang, Jin Hyun Kim, Oliver S. Hutter, Laurie J. Phillips, Jeiwan Tan, Jaemin Park, Hyungsoo Lee, Jonathan D. Major, Jae Sung Lee, Jooho Moon
Abstract
Abstract Determining cost-effective semiconductors exhibiting desirable properties for commercial photoelectrochemical water splitting remains a challenge. Herein, we report a Sb 2 Se 3 semiconductor that satisfies most requirements for an ideal high-performance photoelectrode, including a small band gap and favourable cost, optoelectronic properties, processability, and photocorrosion stability. Strong anisotropy, a major issue for Sb 2 Se 3 , is resolved by suppressing growth kinetics via close space sublimation to obtain high-quality compact thin films with favourable crystallographic orientation. The Sb 2 Se 3 photocathode exhibits a high photocurrent density of almost 30 mA cm −2 at 0 V against the reversible hydrogen electrode, the highest value so far. We demonstrate unassisted solar overall water splitting by combining the optimised Sb 2 Se 3 photocathode with a BiVO 4 photoanode, achieving a solar-to-hydrogen efficiency of 1.5% with stability over 10 h under simulated 1 sun conditions employing a broad range of solar fluxes. Low-cost Sb 2 Se 3 can thus be an attractive breakthrough material for commercial solar fuel production.