Selective transport and separation of charge-carriers by an electron transport layer in NiCo2S4/CdO@CC for excellent water splitting

Abstract

Here, we propose an approach to inhibit interfacial charge recombination by an electron transport layer (ETL) that selectively transports electrons and simultaneously restricts the passage of holes. The ETL is embedded as a junction between a photocatalyst (NiCo2S4/CdO) and an electron collector (carbon cloth (CC)). The electron density gradient, band gap offset, and p-orbital states above the fermi level in the ETL regulate the directional flow of electrons from NiCo2S4/CdO to CC. The distinct locations of electrons and holes were confirmed based on the oxidation state and preferential deposition of platinum and lead ions on NiCo2S4/CdO@CC. The molecular orbitals and density of states and their relation to ETL's performance were explained using first principles calculations. Reduction in recombination energy loss was supported by the Nyquist and Bode phase analyses. ETL's inclusion resulted in a remarkable 77 % increase in H-2 yield, suggesting that they have excellent potential for practical applications.