Constructing n-ZnO@Au heterogeneous nanorod arrays on p-Si substrate as efficient photocathode for water splitting

Abstract

Developing ingenious heterostructure photoelectrodes in photoelectrochemical (PEC) cells to both harvest more solar photons and steer desired charge separation flow is a prerequisite challenge for PEC water splitting. Herein a hierarchical p-Si/n-ZnO@Au heterostructure was constructed via large-area growth of one-dimensional (1D) ZnO nanorod arrays (NRAs) on p-Si substrate followed by decorating with Au nanoparticles (NPs), which exhibited remarkably improved photocathode activity for PEC water splitting relative to the bare Si and Si/ZnO NRAs photocathodes. In addition to structural superiorities of 1D NRAs, a series of dynamic contributions from complementary band-gap structure, p-n heterojunctions and Au plasmon towards photon harvesting and charge separation were demonstrated to ensure a well-steered collection of photoelectrons at the exposed ZnO nanorods and Au NPs, enabling substantially improved photocathode performance.

Plasmon‐Dictated Photo‐Electrochemical Water Splitting for Solar‐to‐Chemical Energy Conversion: Current Status and Future Perspectives

“…In particular, ZnO NRs/nanowires (NWs) arrays grown on conducting substrate (e.g., Si, FTO, ITO, or Ti foil) are promising nanostructures for photocatalytic, photovoltaic, and PEC applications. As performed by Hu's group, n‐type ZnO and p‐type Si were combined to construct build‐in electric field in the interfacial region of p–n heterojunction, which benefits separation of photogenerated charge carriers by expediting the poor surface catalytic dynamics. More specifically, hierarchical Si/ZnO/Au ternary heterostructure was fabricated by hydrothermal growth of ZnO nanorods arrays (NAs) on the Si substrate followed by electrostatic assembly of Au NPs on the ZnO NAs.…”

Steering Photoelectrons Excited in Carbon Dots into Platinum Cluster Catalyst for Solar‐Driven Hydrogen Production

“…Applying potentials above the CB to form an accumulation layer, or below the VB to form inversion layers, can result in abrupt emergence of cathodic and anodic currents, respectively. [16] The cathodic and anodic scan profiles ( Figure S5 [41] where Ag/AgCl 0 E is the standard potential of Ag/AgCl reference electrode (0.1976 V vs RHE at 25 °C), E RHE and E Ag/AgCl are the converted potential versus RHE and the measured potential versus Ag/AgCl. The bandgap energy estimated from the potential scans was 2.56 eV, which is close to that obtained from the optical absorption spectrum.…”

“…Applying potentials above the CB to form an accumulation layer, or below the VB to form inversion layers, can result in abrupt emergence of cathodic and anodic currents, respectively . The cathodic and anodic scan profiles (Figure S5, Supporting Information), respectively, estimate the CB and VB potentials of ≈−1.31 and 1.25 eV versus Ag/AgCl electrode, which were then converted to relative values of −0.70 and 1.86 eV to reversible hydrogen electrode (RHE) using a Nernst conversion equation , where is the standard potential of Ag/AgCl reference electrode (0.1976 V vs RHE at 25 °C), E RHE and E Ag/AgCl are the converted potential versus RHE and the measured potential versus Ag/AgCl. The bandgap energy estimated from the potential scans was 2.56 eV, which is close to that obtained from the optical absorption spectrum.…”

Surfactant-assisted hydrothermal synthesis of MoS2 micro-pompon structure with enhanced photocatalytic performance under visible light

“…The absorbance peak intensity of the visible region is weaker than that of the ultraviolet region for the MoS 2 micro-pompon without surfactants. [40,41].…”