Unbiased photoelectrochemical H2O2 coupled to H2 production via dual Sb2S3-based photoelectrodes with ultralow onset potential.

ABSTRACT

The productions of hydrogen peroxide (H2O2) and hydrogen (H2) in a photoelectrochemical (PEC) water splitting cell suffer from an onset potential that limits solar conversion efficiencies. The formation of H2O2 through two-electron PEC water oxidation reaction competes with four-electron oxidation evolution reaction. Herein, we developed the surface selenium doped antimony trisulfide photoelectrode with the integrated ruthenium cocatalyst (Ru/Sb2(S,Se)3) to achieve the low onset potential and high Faraday efficiency (FE) for selective H2O2 production. The photoanode exhibits an average FE of 85% in the potential range of 0.4-1.6 VRHE and the H2O2 yield of 1.01 µmol cm-2 min-1 at 1.6 VRHE, especially at low potentials of 0.1-0.55 VRHE with 80.4% FE. Impressively, an unassisted PEC system that employs light and electrolyte was constructed to simultaneously produce H2O2 and H2 production on both Ru/Sb2(S,Se)3 photoanode and the Pt/TiO2/Sb2S3 photocathode. The integrated system enables the average PEC H2O2 production rate of 0.637 µmol cm-2 min-1 without applying any addition bias. This is the first demonstration that Sb2S3-based photoelectrodes exhibit H2O2/H2 two-side production with a strict key factor of the system, which represents its powerful platform to achieve high efficiency and productivity and the feasibility to facilitate value-added products in neutral conditions.