Z-scheme Bi2SiO5/Ni-doped Ag6Si2O7 heterojunction with remarkable photocatalytic performance for MO degradation with enhanced light absorption ability: Adjustment of electron transfer path and energy band structure

In this paper, a novel Bi2SiO5/Ni-Ag6Si2O7 semiconductor with remarkable visible light absorption ability and electron transfer efficiency was synthesized through ice bath deposition and hydrothermal method. The addition of Ni2+ reduced the particle size of Ag6Si2O7 and increased specific surface area. Under simulated sunlight, the degradation rate of the optimal samples for MO reached 0.03743 min−1, which was 7.28 times, 3.15 times and 1.56 times than that of Bi2SiO5 and Ag6Si2O7 and Bi2SiO5/Ag6Si2O7, respectively. The formation of Z-scheme heterojunction inhibited the photoinduced carrier recombination, promoted the generation of active free radicals and preserved high redox capacity of photogenerated carriers. According to the density functional theory (DFT) and M−S test, an intermediate doping energy level was introduced to Ag6Si2O7, which acted as the capture center of photogenerated carriers and effectively adjusted the energy band structure. The impurity energy level further inhibited the recombination of carriers and promoted the electron transfer in the Z-scheme transfer mechanism. Moreover, the introduction of Ni2+ further enhanced the visible light response of photocatalysts. Therefore, the improved photocatalytic ability was assigned to the introduction of Ni2+ ions based on the formation of heterojunction.