Synergistic coupling of piezoelectric and plasmonic effects regulates the Schottky barrier in Ag nanoparticles/ultrathin g-C3N4 nanosheets heterostructure to enhance the photocatalytic activity

Although plasmonic metal can provide energetic hot electrons by localized surface plasmon resonance (LSPR) effect in plasmonic metal/semiconductor systems during photocatalysis, the high Schottky barrier limits the electron migration at the interface, which is a scientific problem to be solved urgently. Herein, we employed the cooperative piezoelectric field in the plasmonic metal/semiconductor composite system to provide the strain, which can generate a polarized charge that attracts free electrons at the interface, thus moving the band edge down and facilitating the interfacial transfer of the electrons. As a demonstration case of this idea, Ag nanoparticles/ultrathin g-C3N4 nanosheets (Ag/UTCN) were constructed for realizing the synergistic plasmonic and piezoelectric effect, exhibiting the significantly enhanced photocatalytic activity, and the optimal photocatalytic TC degradation rate reached 93.7% and H2 production rate reached 2615 μmol h−1 g−1, respectively. Results of photochemical analysis illustrated that the semiconductor (in the case of UTCN nanosheets) with piezoelectric properties is employed to couple the plasmonic metal (in the case of Ag nanoparticles), which can enable more hot electron injection into the conduction band of the semiconductor to achieve effective carrier separation. This strategy provides a feasible solution for enhancing the efficiency of the photocatalytic system through the synergy of multiple fields.