Precision engineering of interfacial wettability on bismuth molybdate via an in situ protic ionic liquid coating for ultra-efficient oxidative desulfurization

The development of high-performance oxidative desulfurization (ODS) catalysts is often hindered by inefficient mass transfer across oil-water-solid interfaces and a reliance on complex multi-step syntheses. While surface hydrophobization is a recognized solution, existing methods lack simplicity and precision. This study introduces a fundamental advance: a one-pot in-situ strategy to precisely engineer the wettability of bismuth molybdate (BMO) by forming a protic ionic liquid (PIL) coating from oleic acid (OA) and oleylamine (OLA). The water contact angle of hydrophobic BMO could be controllably tuned from 27.8° to 104.9° by increasing the content of OA and OLA. Comprehensive characterizations confirm the successful formation and incorporation of PIL without altering the crystal structure. The optimized hydrophobic BMO achieved complete removal of dibenzothiophene within 30 min under mild ODS conditions, and also exhibited high selectivity and good recyclability. Mechanistic studies indicated that peroxomolybdate species rather than free radicals are the active intermediates. This work provides a promising strategy for the hydrophobic modification of hydrophilic metal oxides and the construction of efficient heterogeneous catalytic systems.