Multiple effects of nano-carbon coating on mediating Schottky barrier height, inhibiting Ti3C2 oxidation and elevating photocatalytic activity in BiOBr/carbon-coated Ti3C2/exfoliated bentonite

Abstract

Exploiting effective and durable Ti3C2-based co-catalysts, meanwhile properly adjusting Schottky barrier at the junction between co-catalysts and semiconductors, was crucial for facilitating the transfer of photogenerated electrons. The new Ti3C2/exfoliated bentonite (Ti3C2/BTex) severed as a superior co-catalyst was confirmed in our previous study. Nonetheless, insufficient antioxidant capacity and upper Schottky barrier height (SBH) between Ti3C2/BTex and photocatalyst were critical problems needed to be addressed. Herein, we propose a novel carbon-coating strategy to reduce the SBH by constructing a fast electron transfer channel and enhancing the co-catalysts antioxidant capability through the physical barrier effect of carbon layer. Carbon-coated Ti3C2/exfoliated bentonite (C@Ti3C2/BTex) was firstly synthesized, followed by self-assembling BiOBr on the surface of C@Ti3C2/BTex to construct a novel BiOBr/C@Ti3C2/BTex. Several fluoroquinolones (FQs) antibiotics were effectively removed by BiOBr/C@Ti3C2/BTex, and 94 % of Moxifloxacin (MOX) was degraded within 120 min under light irradiation. Based on band structures analysis and photoelectrochemical test results, the enhanced in separation and migration of photogenerated carriers could be attributed to the synergistic effects of reducing of SBH at the heterojunction and surface charge repulsion supplied by BTex. Moreover, the high tolerance to complex water disturbances, superior recyclability and stability were revealed in BiOBr/C@Ti3C2/BTex. The crucial intermediates and three degradation pathways of MOX during photocatalytic degradation were also elucidated. The work presented an effective method to optimize the heterojunction interface contact between Ti3C2 and a photocatalyst using a carbon-coating strategy, and new insights into the design of stable and efficient Ti3C2-based co-catalysts.