Photoanode synthesis of ammonia based on a light reflex strategy and NiCe-layered double hydroxide and oxygen-vacancy Bi2O3 catalysts

Photoelectrocatalysis or photoelectrochemistry (PEC) strategies to synthesize NH3 by nitrogen reduction reaction (NRR) have attracted considerable attention in recent years, but the PEC-NRR synthesis of NH3 on photoanodes (vs commonly used photocathodes) is still a rather new topic worthy of in-depth study. Herein, the high-performance PEC-NRR synthesis of NH3 is achieved on an oxygen-vacancy Bi2O3 and then NiCe-layered double hydroxide modified fluorine-doped tin oxide photoanode biased at 0.4 V vs KCl-saturated calomel electrode, and the utilization of light source is improved by an Ag-mirror-film based light reflex. Under optimal conditions, the yield of NH3 is 16.9 mmol h−1 m−2, and it is increased to an apparent value of 27.8 mmol h−1 m−2 after counting the NRRs on both the photoanode and the Pt counter electrode, revealing that the photoanode strategy is promising for the green and sustainable synthesis of NH3 under ambient conditions. The NH3-synthesis mechanism is discussed after various characterizations and theoretical calculations.