Unbiased Photoelectrochemical HO Coupled to H Production via Dual SbS-Based Photoelectrodes with Ultralow Onset Potential.

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