Enhanced CO2-to-methane photoconversion over carbon nitride via interfacial charge kinetics steering

Abstract

Serious carrier recombination and limited active sites are the main restrictions on the efficiency of CO2 photoconversion over g-C3N4-based photocatalysts. Herein, a unique tubular C3N4-carbon heterostructure was constructed via thermal polycondensation process, where the inherent open porous C3N4 microstructure was rationally exploited as scaffolds to co-assemble with pyridinic N moieties into composites. Beyond the critical role of serving as a carbon source, the EDTA-2Na additive provides a fairly straightforward pathway for the production of surface cyano groups, which presumably results from the dehydration process of amide bonds. The interfacial cyano groups and work function difference induce strong built-in electric field effects, boosting spatial carrier transfer kinetics. Meanwhile, the incorporated reactive N species endow high affinity for CO2 and thereby remarkable enhancement of uptake capacity. The developed hybrid system modulates the CO2 reduction pathway with favoured 8e− selectivity (56%) toward CH4 products, with an evolution rate up to 2.54 μmol·g-1 h−1, compared with trace of the bare C3N4 counterpart. This work constitutes a prospective target for surface and interface design and paves the way for developing high-performance photocatalysts for multi-electron CO2 reduction.

Keywords

• C3N4-carbon heterostructure
• Photocatalysis
• CO2 reduction
• Carrier transfer kinetics
• Methane product