One-dimensional Au/SiC heterojunction nanocomposites with enhanced photocatalytic and photoelectrochemical performances: Kinetics and mechanism insights

In this work, highly dispersed Au nanoparticles (NPs) decorated SiC nanowires (NWs) hybrids were firstly synthesized by a facile deposition-precipitation method. The as-prepared Au/SiC samples were characterized using various instrumental methods such as XRD, TEM, EDS, UV–vis DRS, BET, FTIR, XPS, PL, TRPL, and photoelectronchemical measurements. The solar H2 production performances were investigated by using Na2S as sacrificial reagents in water under simulated sunlight illumination produced from a 300 W xenon lamp. Results showed that a significantly enhanced photoactivity for H2 evolution (1495.8 μmol h−1·g−1) with apparent quantum efficiency (AQE) of 2.12% was achieved over the compostion-optimized Au/SiC composite (with 0.5 wt% Au), which was much higher than those of pure SiC NWs, Pt NPs deposited SiC NWs sample as well as the previously reported SiC-based catalysts. In cyclic tests, the AS0.5 showed acceptable photocatalytic stability and good structural stability. PL, TRPL and photoelectrochemical measurements disclosed that improved charge separation and retarded charge recombination were realized. However, the Au-loaded SiC products with strong surface plasmon resonance (SPR) absorption showed no activity for visible light photocatalytic H2 production (λ ≥ 400 nm). Based on band-gap structures, the critical factors for SPR effect of Au NPs in activating or enhancing the visible-light photoactivities of semiconductors were proposed. This work can pave the avenue to the development of plasmonic metal decorated other narrow band gap semiconductors with plasmon-enhanced visible-light photoactivity for solar water splitting and related applications. [Display omitted] •A deposition-precipitation method was used to prepare Au/SiC nanohybrids.•The enhanced charge transfer and separation efficiency of Au/SiC was achieved.•Au/SiC hybrids showed improved photocatalytic and photoelectrochemical activity.•Mechanisms of improved performances over Au/SiC were proposed and discussed.•Au played an electron tank role in boosting the activity of SiC rather than SPR role.