Unraveling compensation between electron transfer and strain in Ni-Ag-MoS₂ photocatalyst

Despite the boom in catalytic response via constructing interfaces, understanding interfaces’ interaction in heterostructures is still a paradox. In this work, the interaction of Ni with MoS₂ in Ni-Ag-MoS₂ heterostructure are unveiled through synchrotron X-PEEM and what's more, the missing interaction mechanism at the Ag-MoS₂ interface is probed via Raman mapping. The observed competition between the downshift of the E_2g¹ and A_1g modes due to charge carrier injection and the upshift of the E_2g¹ and A_1g modes due to compressive strain during reverse laser power experiment is assigned to the non-uniform growth of Ag nanoparticles, their intimate contact with MoS₂, and Ag intercalated layered MoS₂. The substantial improvement of the H₂ yield of the Ni-Ag-MoS₂ (∼55 μmol h⁻¹ g⁻¹) over the pristine MoS₂ and the binary Ag-MoS₂ evidence successful bonding of Ni, Ag and MoS₂. This study highlights the importance of considering both electronic coupling and strain to optically tune electromechanical properties of MoS₂.