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

Solar-driven N2 fixation offers a green alternative to the highly energy-intensive Haber-Bosch process that re-leases more than 300 million metric tons of CO2 annually to form NH3. However, N2-reducing photo-electrochemical (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.

Automated summary

Solar-driven N2 fixation provides a green alternative to the energy-intensive Haber-Bosch process, but the effect of oxidation reaction on N2 reduction has not been investigated in N2-reducing photo-electrochemical (PEC) studies. In this study, a bias-free PEC platform for N2 reduction and H2O oxidation was developed, and valuable chemicals were simultaneously synthesized on both electrodes using N2, H2O, and sunlight. This work represents the first example of a PEC NRR platform coupled with H2O oxidation and H2O2-dependent oxygenation for unbiased chemical synthesis.