Promotion of Photocatalytic Hydrogen Evolution under Visible Light with NiO/C Fabricated via a Super Facile and General Strategy

Exploration of efficient, cost-effective, abundant, and environmentally friendly catalysts for generating clean and renewable energy resources is currently highly needed. Here, we designed a photocatalyst based on nickel oxide(II) nanoparticles embedded in a carbon matrix for the photocatalytic hydrogen evolution reaction (pHER). A super facile fabrication strategy involves using only one nontoxic substrate (nickel acetate) as a simultaneous source of nickel and carbon. The catalyst with tuned morphology (via process time) showed a superior pHER performance yielding 7.4 mmol/h, an effect of synergy between nickel nanoparticles and graphitic carbon. The synergy comes from (i) the conductive properties of carbon, (ii) defects present in the carbon matrix, which act as hydrogen evolution sites, and (iii) NiO nanoparticles, which improve charge carrier separation increasing the H2 evolution rate. The mechanism of pHER was proposed based on an ex situ study of the postprocessed catalyst with electron paramagnetic resonance spectroscopy (EPR), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). What is more, we propose a general and super simple approach to deliver carbon/metal oxide composites from different metal acetates to deliver catalytically active materials with tunable physicochemical properties that can meet the requirements of different processes.