Association study between the optical-photocatalysis behaviors and the carrier transfer characteristics of g-C3N4/Sr2MgSi2O7:(Eu,Dy)

Continuous photocatalysis is achieved by using light-storing assisted photocatalytic composites, but little is known about the interactions between photocatalysts and long afterglow materials. g-C 3 N 4 /Sr 2 MgSi 2 O 7 :(Eu,Dy) with a sustained reaction activity was prepared by pyrolysis polymerization, and its optical-photocatalysis behaviors were studied. It was found that the light absorption ability and NO removal effect were improved, but the luminescence-afterglow performance became worse. The interface model of g-C 3 N 4 /Sr 2 MgSi 2 O 7 :(Eu,Dy) was constructed for the first time. On the basis of experimental analyses, its electronic structure and carrier transfer paths were studied by First-principles calculations, and reasons behind the changes in macro performance were revealed. The results showed that Eu 4 f electrons are difficult to return to the Eu 5d orbits after being captured by C 2p orbits, leading to the reduction of light energy radiation; the built-in electric field and energy band offsets between g-C 3 N 4 and Sr 2 MgSi 2 O 7 :(Eu,Dy) promote the transfer of photoinduced carriers, which follows a traditional type-II mechanism, resulting in enhanced photocatalytic activity and decreased luminescence-afterglow performance. This paper reveals the relationship between optical-photocatalysis behaviors and the electronic structure of g-C 3 N 4 /Sr 2 MgSi 2 O 7 :(Eu,Dy). It provides a reference for designing and optimizing light-storing assisted photocatalytic composites. • After turning off the light, the catalytic reactions of g-C 3 N 4 /Sr 2 MgSi 2 O 7 :(Eu,Dy) can continue. • Sr 2 MgSi 2 O 7 :(Eu,Dy) phosphor has the ability of photocatalytic removal of NO. • The interface model of g-C 3 N 4 /Sr 2 MgSi 2 O 7 :(Eu,Dy) was constructed for the first time. • The capture of Eu 4 f electrons by C 2p orbits leads to the reduction of light energy radiation. • The carrier transfer in g-C 3 N 4 /Sr 2 MgSi 2 O 7 :(Eu,Dy) follows a type-II mechanism.