Enhancement of Photoredox Activity by F/N Synergistic Co-Doping of Black Amorphous Carbon Nanostructures.

Abstract

Black carbon materials are widely used due to their low cost, abundance, and easy modification, but their photocatalytic application is limitedss by rapid solar-to-thermal conversion. Here, synergistic F/N co-doping was developed to enhance the photocatalytic performance of amorphous carbon materials (aCMs) by creating charge localization sites that promote electron-hole separation. Kelvin probe force microscopy (KPFM) and surface photovoltage (SPV) measurements indicate that F/N co-doping can establish a stronger internal electric field within the aCMs. A comprehensive suite of spectroscopic analyses reveal that the F/N-aCMs exhibits a lower exciton binding energy (14.60 meV), faster relaxation time of photoexcited electrons from the conduction band minimum to the exciton-mediated trap state (3.98 ps), and a longer carrier lifetime (3.93 ns), demonstrating significantly enhanced efficiency in charge carrier separation. Density functional theory (DFT) calculations confirm F/N co-doping reduces electron-hole overlap and lowers the energy barrier for superoxide radical (•O₂ ^-) generation. Remarkably, photocatalytic experiments not only confirm the high activity of F/N-aCMs in aldehyde oxidation (with 87%-99% yields across 22 substrates) but also demonstrate an acceptable apparent quantum yield (1.78%) and superior solar-to-chemical conversion efficiency (0.37%). This work opens up a new direction for the rational design of aCMs for photocatalytic organic synthesis.