Novel Heterostructure of CdSe Nanobridge on ZnO Nanorods: Cd-Carboxyl-RGO-Assisted Synthesis and Enhanced Photoelectrochemical Efficiency

Abstract

Photoelectrochemical (PEC) hydrogen generation is a green and effective strategy for addressing energy crises. In this study, a CdSe heteronanobridge (HNB) structure is fabricated as PEC photoanode via a hydrothermal method. The "pier" is built using ZnO nanorods (NRs) decorated with CdSe nanoparticles (NPs), and the "bridge" is constructed using CdSe nanowire covered by an reduced graphene oxide (RGO) layer and cross-linked with ZnO NRs. The formation of the CdSe NBs is ascribed to the passivation of the CdSe nonpolar surface with an RGO layer by the formation of Cd-carboxyl-RGO bond in alkaline solution, which directs the preferential growth of CdSe along c-axis. Additionally, despite etching the functionalized RGO with HAuCl 4 solution, CdSe NBs decorated with Au NPs are also synthesized as another heteronanostructure. This study demonstrates that the photoconversion of the CdSe hetero-NBs can be enhanced via the type II cascade band alignment of CdSe and ZnO and efficient charge transfer through net-like bridge structures. Moreover, the Cd-carboxyl-RGO layer and Au NPs can improve the electron lifetime of the CdSe NBs by suppressing electron-hole recombination. Overall, CdSe hetero-NBs with increased PEC efficiency represent a promising photoanode material, and the synthesis route can be used to build highly networked heteronanostructures of other materials.