Insightful understanding of charge carrier transfer in 2D/2D heterojunction photocatalyst: Ni-Co layered double hydroxides deposited on ornamental g-C3N4 ultrathin nanosheet with boosted molecular oxygen activation.

[Display omitted] • Ni-Co LDH/C, O co-doped g-C 3 N 4 2D/2D heterojunction has been first fabricated. • The modification of 2-methylimidazole enhanced photoconversion efficiency. • 2D/2D heterojunction exhibits excellent molecular oxygen activation. • The formed charge carrier transfer pathway promotes photoelectron transfer. • 2D/2D heterojunction possesses weakened surface charge carrier recombination. Molecular oxygen is a green and low-cost oxidant, which can be activated to produce reactive oxygen species by solar-light-driven photocatalysis. Here, Ni-Co LDH infused C, O co-doped g-C 3 N 4 two-dimensional (2D) ultrathin nanosheet was prepared by a simple thermal polymerization coupling hydrothermal method. The molecular oxygen activation was estimated by the quantitative determination of •O 2 − and 3,3′,5,5′-tetramethylbenzidine (TMB) oxidation. 2D/2D heterojunction exhibits impressive photocatalytic performance. The arrestive activation efficiency is derived from the regulated energy band position, the broadened solar light absorption range, and the enhanced photoexcited electron transfer. Benefitting from these merits, the surface charge transfer efficiency of 2D/2D heterojunction is promoted to 51.3% from 14.3% (g-C 3 N 4). The surface recombination rate constant is reduced to 0.0011 s−1 from 0.0042 s−1 (g-C 3 N 4). The feasible photocatalytic mechanism for molecular oxygen activation is expounded based on experimental analysis. [ABSTRACT FROM AUTHOR]