Unbiased Photoelectrochemical H2O2 Coupled to H2 Production via Dual Sb2S3‐Based Photoelectrodes with Ultralow Onset Potential

Abstract The productions of hydrogen peroxide (H 2 O 2 ) and hydrogen (H 2 ) in a photoelectrochemical (PEC) water splitting cell suffer from an onset potential that limits solar conversion efficiencies. Moreover, the formation of H 2 O 2 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/Sb 2 (S,Se) 3 ) to achieve the low onset potential and high Faraday efficiency (FE) for selective H 2 O 2 production. The photoanode exhibits an outstanding average FE of 85 % in the potential range of 0.4–1.6 V RHE and the H 2 O 2 yield of 1.01 μmol cm −2 min −1 at 1.6 V RHE , especially at low potentials of 0.1–0.55 V RHE with 80.4 % FE. Impressively, an unassisted PEC system that employs light and electrolyte was constructed to simultaneously produce H 2 O 2 and H 2 production on both the Ru/Sb 2 (S,Se) 3 photoanode and the Pt/TiO 2 /Sb 2 S 3 photocathode. The integrated system enables the average PEC H 2 O 2 production rate of 0.637 μmol cm −2 min −1 without applying any addition bias. To our knowledge, this is the first demonstration that Sb 2 S 3 ‐based photoelectrodes exhibit H 2 O 2 /H 2 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.