In-situ growth of TiO2 imbedded Ti3C2TA nanosheets to construct PCN/Ti3C2TA MXenes 2D/3D heterojunction for efficient solar driven photocatalytic CO2 reduction towards CO and CH4 production

[Display omitted] •New approach for synthesis of exfoliated 2D Ti3C2TA MXenes based PCN composite.•In-situ growth of TiO2 NPs imbedded over Ti3C2 obtained through HF etchant of 48 and 96 h.•2D/2D Ti3C2TA MXene/PCN efficiency was 9.9 folds high than PCN under visible light.•Photo-induced CO2 reduction with H2/methanol promoted CH4 formation than only water.•High stability and reusability in cycles was attained using 2D Ti3C2TA with g-C3N4 catalyst. Constructing efficient structured materials for artificial photosynthesis of CO2 is a promising strategy to produce renewable fuels in addition of mitigating greenhouse effect. In this work, 2D porous g-C3N4 (PCN) coupled exfoliated 3D Ti3C2TA MXene (TiC) nanosheets with TiO2 NPs in-situ growth was constructed in a single step through HF treatment approach. The different exfoliated TiC structures were successfully synthesized for adjusting HF etching time (24 h, 48 h and 96 h). With growing etchant time from 24 to 96 h, the amount of TiO2 produced was increased, but it has adverse effects on CO and CH4 production rate. The maximum production rates for CO and CH4 of 317.4 and 78.55 µmol g−1 h−1 were attained when the 10TiC-48/PCN was employed than using TiC-24/PCN, TiC-96/PCN and PCN composite samples, respectively. The performance of 10TiC-48/PCN composite for CO and CH4 evolution were 9.9 and 6.7 folds higher than using pristine PCN sample, respectively. The possible mechanism is assigned to porous structure with intimate contact enabling efficient charge carrier separation with the role of TiO2 NPs to work as a bridge to transport electrons towards MXene surface. Among the reducing agents, water was favorable for CO evolution, whereas, methanol–water system promoted CH4 production. All these findings confirm that heterojunction formation facilitates charges separation and can be further used in solar energy relating application.