Transition metals decorated g-C3N4/N-doped carbon nanotube catalysts for water splitting: A review

As a metal-free and visible-light-responsive photocatalyst, graphitic carbon nitride (g-C3N4) has been attracting considerable attention recent years due to its outstanding photocatalytic activity, low cost, appealing electronic band structure, high physicochemical stability, earth-abundant nature, and wide applications. The photocatalytic efficiency of g-C3N4 and g-C3N4-based materials involving H2 generation from H2O splitting depends on the separation and transport efficiency of the photogenerated charge carriers. Transition metal modification on g-C3N4/N-doped carbon nanotube-based catalysts offer the possibility of enhancing photo-/electro-catalytic performances of the materials. This review summarizes a panorama of the recent advances in development of gC3N4/N-doped carbon nanotube based catalysts including (1) synthesis of tubular g-C3N4 based catalysts via various methods, e. g., templating method and non-metal and transition metal doping; (2) construction of nanotubes with enhanced photo/electro-chemical water splitting efficiency and investigation of the effects of nonmetal doping on the substrates; (3) the effect of transition metals (e.g., transition metal single atom and metal alloy) modification on the catalytic performances of the nanotubes; (4) recent development in construction of g-C3N4/N-doped carbon nanotube based heterostructures and the photocatalytic applications of the composite materials. The review attempts to cover the latest advances in development of next-generation g-C3N4-based nanotube catalysts.