Ni clusters-derived 2D/2D layered WOx(MoS2)/Ni-g-C3N4 step-scheme heterojunctions with enhanced photo- and electro-catalytic performance

Abstract

Two dimensional/two dimensional (2D/2D) layered heterostructures possess enhanced photo- and electro-catalytic performances due to large contact area that improves interfacial charge transfer. Herein, 2D/2D WOx/Ni-g-C3N4 and MoS2/Ni-g-C3N4 heterostructures are fabricated via mechanical chemical grinding and hydrothermal synthesis, using superior thin N-doped g-C3N4 nanosheets obtained by introducing Ni clusters into bulk g-C3N4 during condensation process. The Ni clusters play the key role in formation of layered heterostructure. WOx consisting mainly of WO3 and limited amount of WO2 can be homogeneously distributed onto g-C3N4 nanosheets to form WOx/Ni-g-C3N4 heterostructures. The heterostructure with optimized WOx ratio exhibits enhanced H2 generation (3.9 mmolg−1h−1) and CO2 reduction rate (4.2 μmolg−1h−1) that is 3 times higher than that of WOx/g-C3N4 heterostructure with no Ni decoration. The enhanced photocatalytic performances are due to the formation of step-scheme heterojunction. Moreover, similar methods are used for synthesizing MoS2/Ni-g-C3N4 heterostructures. In contrast, MoS2/Ni-g-C3N4 heterostructure with optimized MoS2 ratio reveals high stability and activity in electrocatalytic hydrogen evolution reaction (HER). The MoS2/Ni-g-C3N4 electrocatalyst exhibits superior HER activity with low onset potential and small Tafel slope value in both acidic and alkaline condition. The results provide new perspectives on designing and constructing novel heterojunction catalysts.