Defects induced efficient overall water splitting on a carbon-based metal-free photocatalyst

TLDR: In this paper, a carbon photocatalyst with abundant carbon defects created by removing the nitrogen atoms from a N-doped precursor was presented, which then work as oxidation sites for O2 generation.

Abstract: Hydrogen production from overall water splitting by photocatalyst is an ultimate clean and renewable energy strategy. Recent developments show that carbon based materials are considerable photocatalysts for overall water splitting under visible light because of their high activity, high stability, low-cost, easy fabrication and structural diversity. However, it still lacks a systematic study and deep understanding on the working mechanism of the carbon based photocatalysts. Herein, we show the fabrication of a carbon photocatalyst with abundant carbon defects created by removing the nitrogen atoms from a N-doped precursor. The active defects bond with water molecules during the photocatalytic reaction, which then work as oxidation sites for O2 generation. We also demonstrate an accessible strategy to produce more defects to observably enhance the photocatalytic activity (around 10 times) as well as to select between the 2-electron/2-electron and the 4-electron pathway water splitting. The synthesized photocatalyst is efficient in photocatalytic visible-light overall water splitting with an optimum H2 and O2 production of 2.54 and 1.25 μmol h−1, respectively. Moreover, the quantum efficiency and solar to hydrogen (STH) efficiency were measured to be 2.04% for wavelength λ = 420 ± 20 nm and 0.1% using AM 1.5 G, respectively.