Coordinatively unsaturated bismuth sites accelerate in-situ hydrogen peroxide electrochemical formation for efficient butanone oxime synthesis

Selective electrochemical water oxidation via a 2e- pathway represents a sustainable H2O2 electrosynthesis route. However, the low activity and selectivity due to competing 4e- oxygen evolution and challenges in separating in-situ-generated H2O2 for subsequent reactions. Herein, we develop an unsaturated coordinative bismuth-benzene tricarboxylic acid metal-organic framework using a hetero-linker doping strategy. The catalyst demonstrates enhanced performance in selective H2O2 synthesis, achieving a low overpotential of 0.98 V and high selectivity with a Faradaic efficiency of 79.1%. The accumulated ~6.17 wt.% H2O2 enables an efficient direct conversion of butanone ammoximation to butanone oxime, showing a high conversion rate of 80.2% and a selectivity of 81.1%. Structural characterizations reveal the unsaturated coordination in the central bismuth atoms. These unsaturated coordinative bismuth sites modulate the OH* intermediate adsorption and optimize the free energy of OH* → H2O2, as revealed by in-situ attenuated total reflection Fourier transform infrared spectroscopy and theoretical calculations. This work provides a strategy for rationalizing selective 2e- water oxidation catalysts and advances the industrially valuable reaction for value-added chemicals production.