Anion–Cation Co-Doped g-C(3)N(4) Porous Nanotubes with Efficient Photocatalytic H(2) Evolution Performance

Graphitic C(3)N(4)-based materials are promising for photocatalytic H(2) evolution applications, but they still suffer from low photocatalytic activity due to the insufficient light absorption, unfavorable structure and fast recombination of photogenerated charge. Herein, a novel anion–cation co-doped g-C(3)N(4) porous nanotube is successfully synthesized using a self-assembly impregnation-assisted polymerization method. Ni ions on the surface of the self-assembly nanorod precursor can not only cooperate with H(3)P gas from the thermal cracking of NaH(2)PO(2) as an anion–cation co-doping source, but, more importantly, suppress the shape-collapsing effect of the etching of H(3)P gas due to the strong coordinate bonding of Ni-P, which leads to a Ni and P co-doped g-C(3)N(4) porous nanotube (PNCNT). Ni and P co-doping can build a new intermediate state near the conduction band in the bandgap of the PNCNT, and the porous nanotube structure gives it a higher BET surface area and light reflection path, showing a synergistic ability to broaden the visible-light absorption, facilitate photogenerated charge separation and the light-electron excitation rate of g-C(3)N(4) and provide more reaction sites for photocatalytic H(2) evolution reaction. Therefore, as expected, the PNCNT exhibits an excellent photocatalytic H(2) evolution rate of 240.91 μmol·g(−1)·h(−1), which is 30.5, 3.8 and 27.8 times as that of the pure g-C(3)N(4) nanotube (CNT), single Ni-doped g-C(3)N(4) nanotube (NCNT) and single P-doped g-C(3)N(4) nanotube (PCNT), respectively. Moreover, the PNCNT shows good stability and long-term photocatalytic H(2) production activity, which makes it a promising candidate for practical applications.