S-scheme mesoporous Li2MnO3/g-C3N4 heterojunctions as efficient photocatalysts for the mineralization of trichloroethylene in aqueous media

[Display omitted] •Li2MnO3/g-C3N4 nanocomposites were synthesized through hard and soft templates.•Mineralization of TCE over Li2MnO3/g-C3N4 under visible illumination was achieved.•3% Li2MnO3/g-C3N4 showed better photodegradation efficiency ∼ 100%.•The degradation rate of 3% Li2MnO3/g-C3N4 was ∼five times higher than g-C3N4.•Li2MnO3/g-C3N4 can be recycled five times without loss in its performance. Novel mesoporous Li2MnO3/g-C3N4 heterostructures were prepared for the first time by utilizing the sol–gel route in the presence of a nonionic surfactant. TEM and XRD measurements showed that Li2MnO3 (5–10 nm) with monoclinic structures was uniformly distributed onto porous g-C3N4 for the construction of Li2MnO3/g-C3N4 heterojunctions. The obtained photocatalysts were assessed for mineralization and removal of trichloroethylene (TCE) in aqueous media under visible light exposure. Complete degradation of TCE over a 3 %Li2MnO3/g-C3N4 heterostructure within 120 min was achieved. The degradation rate over Li2MnO3/g-C3N4 heterostructures was significantly enhanced, and the 3% Li2MnO3/g-C3N4 heterostructure exhibited a large degradation rate of 7.04 µmolL−1 min−1, which was enhanced by 5 and 3.8 fold compared to those of pristine g-C3N4 (1.39 µmolL−1 min−1) and Li2MnO3 (1.85 µmolL−1 min−1), respectively. The photocatalytic efficiency of the Li2MnO3/g-C3N4 heterojunction was outstandingly promoted because integrating Li2MnO3 with g-C3N4 could create close interfaces with well-matched band potentials for easy mobility and low recombination of photoinduced carriers. The coexistence of Li2MnO3/g-C3N4 interfaces led to a synergic effect, which is considered the key factor in photoinduced electron-hole separation. The synthesis procedure that was employed here is a promising process for the preparation of effective g-C3N4-based photocatalyst systems for photocatalysis applications.