Controlled Ni doping on a g-C 3 N 4 /CuWO 4 photocatalyst for improved hydrogen evolution.

The development of a low-cost, environment-friendly and suitable semiconductor-based heterogeneous photocatalyst poses a great challenge towards extremely competent and substantial hydrogen evolution. A series of environment-friendly and proficient S-scheme Ni-doped CuWO 4 nanocrystals supported on g-C 3 N 4 nanocomposites (Ni-CuWO 4 /g-C 3 N 4 ) were constructed to ameliorate the photocatalytic efficacy of pure g-C 3 N 4 and Ni-CuWO 4 and their activity in H 2 generation through photocatalytic water splitting was evaluated. The Ni-CuWO 4 nanoparticles were synthesized through doping of Ni 2+ on wolframite CuWO 4 crystals via the chemical precipitation method. An elevated hydrogen generation rate of 1980 μmol h -1 g -1 was accomplished over the 0.2Ni-CuWO 4 /g-C 3 N 4 (0.2NCWCN) nanocomposite with an apparent quantum yield (AQY) of 6.49% upon visible light illumination ( λ ≥ 420 nm), which is evidently 7.1 and 17.2 fold higher than those produced from pristine g-C 3 N 4 and Ni-CuWO 4 . The substantial enhancement in the photocatalytic behaviour is primarily because of the large surface area, limited band gap energy of the semiconductor composite and magnified light harvesting capability towards visible light through the inclusion of g-C 3 N 4 , thus diminishing the reassembly rate of photoinduced excitons. Further, density functional theory (DFT) calculations were performed to investigate the structural, electronic and optical properties of the composite. Theoretical results confirmed that the Ni-CuWO 4 /g-C 3 N 4 composite is a potential candidate for visible-light-driven photocatalysts and corroborated with the experimental findings. This research provides a meaningful and appealing perspective on developing cost-effective and very proficient two-dimensional (2D) g-C 3 N 4 -based materials for photocatalytic H 2 production to accelerate the separation and transmission process of radiative charge carriers.