Benchmark performance of low-cost Sb2Se3 photocathodes for unassisted solar overall water splitting

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-tohydrogen 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.

A Novel Thermochemical Metal Halide Treatment for High-Performance Sb2Se3 Photocathodes

“…Antimony (III) selenide (Sb 2 Se 3 ) has recently emerged as an eco-compatible and low-cost absorber material for various photo-assisted applications due to its advantageous optoelectronic properties ( E g ~1.2 eV, absorption coefficient > 10 5 cm −1 , high mobility) [ 7 , 17 , 18 , 19 , 20 , 21 ]. Besides, Sb 2 Se 3 is internally stable towards photocorrosion, and its elemental composition suggests less-complicated chemistry within the device processing compared to the multielement compounds such as CIGS and CZTS [ 7 , 10 , 22 ]. All these signs indicate the great potential of Sb 2 Se3 for commercial high-performance PEC water splitting devices.…”

“…However, in practice, Sb 2 Se 3 tends to form a nanostructured morphology originating from its crystal structure rather than compact films [ 23 ], which requires unconventional strategies to improve the performance. Recently, compact thin-film Sb 2 Se 3 photocathodes have demonstrated a record photocurrent density of 30 mA cm −2 at 0 V against the reversible hydrogen electrode (RHE) [ 22 ], even though the first value of 2 mA cm −2 at 0 V RHE was reported in 2016 [ 23 ].…”

“…Despite significant efforts for improving the properties of typical absorber layers by various post-depositional treatments (PDTs) experienced for TFSCs [ 8 , 24 , 25 , 26 , 27 , 28 ], the procedures and their productivities of stable absorber/electrolyte interface are limited [ 29 ]. To date, most devices utilizing Sb 2 Se 3 layers exhibited parameters significantly below expectations [ 17 , 18 , 19 , 20 , 21 , 22 , 30 , 31 ]. The current record photocurrent density for compact Sb 2 Se 3 photoelectrodes has been predominantly attained by improvements in deposition methods in preference to realizing any suitable PDTs [ 22 ].…”

“…To date, most devices utilizing Sb 2 Se 3 layers exhibited parameters significantly below expectations [ 17 , 18 , 19 , 20 , 21 , 22 , 30 , 31 ]. The current record photocurrent density for compact Sb 2 Se 3 photoelectrodes has been predominantly attained by improvements in deposition methods in preference to realizing any suitable PDTs [ 22 ]. There have been some attempts to improve the structural properties of Sb 2 Se 3 films by post-deposition selenization, yielding the solar cell efficiency of 6.06% that is still much below theoretical limits [ 31 ].…”

Tailoring the Surface Properties of Bi2O2NCN by in Situ Activation for Augmented Photoelectrochemical Water Oxidation on WO3 and CuWO4 Heterojunction Photoanodes

“… 2 − 7 One such pathway uses PEC cells to obtain hydrogen from water upon solar illumination. 7 − 10 Photochemical water-splitting includes the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), which have to be accomplished simultaneously. 11 Kinetics and stability are considered to be critical issues in the water-splitting process, which limits the PEC water-splitting efficiency.…”