Photoelectrocatalytic N2 fixation and C-H oxyfunctionalization driven by H2O oxidation

Abstract

Solar-driven N2 fixation offers a green alternative to the highly energy-intensive Haber-Bosch process that releases more than 300 million metric tons of CO2 annually to form NH3. However, N2-reducing photoelectrochemical (PEC) studies have not elucidated how an oxidation reaction affects the N2 reduction reaction (NRR). Here, we report a bias-free PEC platform for N2 reduction to NH3 and H2O oxidation to O2 and H2O2. Under solar light, the molybdenum-doped bismuth vanadate-based photoanodes extract electrons from H2O and transfer them to the silicon photovoltaic-wired hematite photocathode. The light-absorbing cathode receives the electrons to drive the NRR, which is influenced by the H2O oxidation reaction’s conditions. Furthermore, the integration of PEC NRR with H2O2-dependent biocatalytic oxyfunctionalization achieves simultaneous synthesis of valuable chemicals on both electrodes. This work presents the first example of a PEC NRR platform coupled with H2O oxidation and H2O2-dependent oxygenation for unbiased chemical synthesis using N2, H2O, and sunlight.