Construction of dual electron channels and multiple active sites in Co-In/Bi/BiOBr for enhanced photocatalytic ammonia production

Abstract

Facilitating electron transfer and charge separation through interfacial engineering is an effective technique for enhancing the activity of nitrogen-fixing photocatalysts. In this paper, nanoflower-like BiOBr (BOB) photocatalysts loaded with Co-In alloys and Bi nanoparticles were successfully prepared by wet chemical reduction and one-step hydrothermal reaction. The presence of dual electron channels on the optimized Co-In/Bi/BiOBr (Co-In/Bi/BOB) catalysts – ohmic contact between Bi/BiOBr (Bi/BOB) and ohmic contact between Co-In/BiOBr (Co-In/BOB) – accelerated the interfacial electron transport rate and effectively promoted charge separation. As a result, the optimal Co-In/Bi/BOB heterostructures have an apparent quantum efficiency of 3.8 % at 420 nm and a nitrogen fixation efficiency of 1023.1 μmol g⁻¹ h⁻¹ in pure water without sacrificial reagent, which is nearly 13.4-fold enhancement compared to pure BOB. DFT calculations show that the introduction of Co-In alloy effectively promotes charge redistribution, and the synergistic effect of bimetallic active sites and oxygen vacancies significantly enhances photocatalytic performance. This study provides a new idea for designing high-performance nitrogen fixation photocatalysts with multiple active sites and electron transport channels.