In situ growth of ultrasmall MoO3 nanoparticles into 3D porous reduced graphene oxide for efficient oxidative desulfurization of high-sulfur

In this study, a novel strategy was developed to synthesize a defect-rich, highly dispersed N, P co-doped molybdenum-based catalyst (MoO 3 /NCG-P) by anchoring phosphomolybdic acid (PMA) clusters onto dopamine (PDA)-modified graphene oxide (GO), followed by thermal treatment. The self-polymerized PDA layer not only served as a nitrogen-rich carbon precursor but also provided abundant anchoring sites for PMA immobilization, while PMA simultaneously acted as both the Mo and P sources. Upon pyrolysis, PMA was in situ decomposed into ultrafine molybdenum trioxide (MoO 3 ) nanoparticles enriched with vacancy defects, and uniformly dispersed on N, P co-doped porous graphene sheets (NCG-P) derived from GO@PDA. This process simultaneously generated strong interfacial coupling and a high density of defect sites, facilitated electron transfer between MoO 3 and the N, P co-doped carbon matrix, endowed the catalyst with enhanced structural stability and excellent surface accessibility. Benefiting from these structural and electronic advantages, in the oxidative desulfurization (ODS) of dibenzothiophene (DBT) using H 2 O 2 as the oxidant, MoO 3 /NCG-P achieved complete removal of 4000 ppm DBT within 20 min at 60 °C, using only 0.03 g of catalyst and a H 2 O 2 /S molar ratio of 2. Furthermore, the catalyst demonstrated excellent reusability, with no significant loss of activity observed over ten consecutive cycles. Mechanistic investigations based on free radical scavenging experiments and in situ electron paramagnetic resonance analysis confirmed that the ODS process predominantly follows a hydroxyl radical-mediated oxidation pathway. These findings offer valuable insights for the design of efficient, stable, and scalable molybdenum-based catalysts for practical ODS applications.