Photocatalytic Hydrogen Evolution Under Visible Light Using an NGCN‐Based System

ABSTRACT In this study, sodium (Na) doped graphitic carbon nitride (NGCN) was synthesized by simple co‐pyrolysis method and explored for photocatalytic H 2 evolution under visible‐light irradiation. The structural, morphological, optical, and surface properties of the prepared materials were investigated by x‐ray diffraction (XRD), scanning electron microscopy (SEM), energy‐dispersive x‐ray (EDX) spectroscopy and elemental mapping, ultraviolet–visible (UV–vis) spectroscopy, photoluminescence (PL) spectroscopy, and Brunauer‐Emmett‐Teller (BET) analysis. EDX analysis confirmed the presence and uniform distribution of Na in NGCN, whereas UV–vis investigations showed a decrease in the optical band gap from 2.70 eV (for pristine GCN) to 2.61 eV (for NGCN). NGCN (15 mg) exhibited hydrogen (H 2 ) evolution of 593 µmol g −1 after 10 h which is higher compared to the pristine GCN (340 µmol g −1 ) The addition of 2 wt% Pt with optimization of the photocatalyst loading and sacrificial reagent, significantly enhanced the H 2 evolution activity. The optimized system containing 80 mg NGCN and 2 wt% Pt achieved H 2 evolution of 7435 µmol g −1 after 10 h in the presence of triethanolamine (TEOA). The prepared photocatalyst maintained comparable performance over four consecutive reuse cycles. These observations show that Na doping may be an efficient strategy for improving the visible‐light photocatalytic performance of NGCN.