Adjustment of the band gap of co-doped KCl/NH4Cl/g-C3N4 for enhanced photocatalytic performance under visible light

The development of a photocatalyst with high activity, large specific surface area and precise band gap adjustment is the focus of the field of photocatalysis in realizing energy conversion and improving environmental issues. In this paper, a simple synthesis process for co-doping of KCl and NH4Cl to precisely adjust the band gap of g-C3N4 was developed. Various characterization results show that doping with KCl and NH4Cl can reduce the band gap of the carbon nitride, increase its visible light absorption, improve its carrier separation efficiency, thus showing good photocatalytic activity. Cl and K enter the g-C3N4 layers via intercalation and form a dual-element charge transport channel between these layers, thereby facilitating the transport of electrons. The introduction of NH4Cl increases the specific surface area of the composite, thus providing abundant adsorption and reaction sites. The co-loaded photocatalyst CN-NH4Cl-0.05KCl was used to degrade rhodamine B (RhB) and tetracycline (TC) and showed excellent photocatalytic activity. A possible mechanism of photocatalytic degradation is proposed based on the analytic results. ▪ •The band gap of g-C3N4 is adjusted by doping with KCl and NH4Cl to suppress carrier recombination.•The introduction of NH4Cl into g-C3N4 is conducive to the formation of mesoporous channels.•Cl and K enter the g-C3N4 layers via intercalation and form a charge transport channel between these layers.•The co-loaded photocatalyst CN-NH4Cl-0.05KCl has an excellent photocatalytic performance.•Possible photocatalytic mechanisms are proposed on the basis of the analytic results.