2D/2D/2D O-C₃N₄/Bt/Ti₃C₂T_x heterojunction with novel MXene/clay multi-electron mediator for stimulating photo-induced CO₂ reforming to CO and CH₄

Controlled fabrication of Ti₃C₂ MXene with unique topology and layered bentonite (Bt) nanoclay to construct a 2D/2D/2D g-C₃N₄/Bt/Ti₃C₂ MXene heterojunction for intriguing photocatalytic CO₂ reduction has been investigated. The MXene/Bt composite exhibits high-light absorption and faster charges separation and transportation. The photoactivity of 2D/2D Ti₃C₂/g-C₃N₄ of 1.38 folds higher than bulk Ti₃AlC₂/g-C₃N₄ obtained due to intimate interface interaction with proficient charges separation. The highest g-C₃N₄/Bt/Ti₃C₂ heterojunction activity for CH₄ evolution of 4.18, 4.42 and 6.96 folds more was achieved compared with g-C₃N₄/Ti₃C₃, Bt/g-C₃N₄ and g-C₃N₄, respectively. This boosted activity was evidently due to Ti₃C₂/g-C₃N₄ Schottky junction with Bt-mediator to provide new electron transfer channels. More interestingly, with proton rich acetic-acid reagent, 4.15 folds more CH₄ production than using only water under prolonged stability was observed. Thus, this study provides a promising approach for clean energy system and potential applications of MXenes/Bt materials for solar fuels production.