Enhanced activity of visible-light photocatalytic H2 evolution of sulfur-doped g-C3N4 photocatalyst via nanoparticle metal Ni as cocatalyst

Abstract

Sulfur doped graphitic carbon nitride g-S-C3N4 (denoted as SCN) was successfully prepared, and the SCN was further combined with metal Ni to prepare the photocatalyst with high visible-light photocatalytic activity. The Ni/g-S-C3N4 (denoted as NiSCN) composite photocatalyst was obtained by photodeposition method. Metal Ni species with the particle size about 5 nm were effectively supported on the surface of SCN. The NiSCN photocatalyst with the optimal Ni loading amounts exhibited an excellent H2-production rate of 2021.3 μmol g−1 h−1 under the visible light (λ > 420 nm). In addition, some Ni atoms might be embedded in the lattice structure of SCN. According to the experimental and computational results, the good utilization of visible light was attributed to the S and Ni doping, which upshifted the VB potential and narrowed the band gap of the photocatalyst. The metal Ni loaded on SCN surface improved the electron transfer rate and charge separation efficiency of the photocatalyst. Then, the H+ in water obtained the electrons on metal Ni to form H2 via the H radical intermediate.