A synergistic strategy to sustainable photoelectrocatalysis through hydrogen peroxide production and sulfur recycling

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Photoelectrochemical (PEC) production of hydrogen peroxide (H2O2) through O2 reduction reaction (ORR) is an up-and-coming alternative to the complicated and energy-intensive anthraquinone process. Herein, an asymmetric PEC cell based on Bi@Sn3O4/Ni foam (NF) photocathode was established to achieve high H2O2 production efficiency and economic feasibility. The as-prepared Bi@Sn3O4/NF possessed a favorable urchin-like micro-nano heterostructure with surface oxygen vacancies and intensive interface Bi-O-Sn bonding for high-efficiency H2O2 production. The two-side production of H2O2 was realized via a PEC cell of Bi@Sn3O4-2/NF ‖ Sn3O4/NF with a lower cell voltage, achieving an overall production of 1350 μM in 2 h with stable current response and a faraday efficiency of 90.5 %. Additionally, the photocathodic H2O2 generation coupled with anodic WS2/carbon paper (CP) for sulfion oxidation reaction (SOR) was also constructed to realize the voltage breakdown and technoeconomic evaluation. The PEC cell of Bi@Sn3O4-2/NF ‖ WS2/CP achieved a total H2O2 production of 4.75 mM and desulfurization for sulfur recycling (82.3 mg) simultaneously after 10 h photoelectrocatalysis, only requiring a low basic electricity expense of 4.1 Wh g−1. The full utilization of cathode and anode in the asymmetric electrolyzer could not only improve the efficiency of PEC transformation for high value-added chemicals, but also save energy consumption simultaneously as a promising sustainable approach.