Investigation of semiconductor-metal heteronanostructured assemblies and their photoelectrochemical properties

Abstract

To reduce carbon dioxide emissions in energy consumption, there is a need to employ renewable energy carriers with no carbon footprint. Heterogeneous catalysts accelerate chemical reactions or facilitate energetically unfavorable ones to produce such renewable energy carriers. Hydrogen, a promissing primary energy carrier, demands energy for its production, which could be sourced from electric or solar energy via electrolyzers or photocatalysts, respectively. This study focused on synthesizing and characterizing novel nanoparticle-based photocatalytic materials, utilizing CdSe and CdS semiconductors in various forms alongside metal cocatalysts. These nanoparticles can form three-dimensional porous gel-like networks, constructed through shock-freezing or chemical destabilization methods. Photoelectrochemical investigations emphasize the importance of homogeneous metal-semiconductor contact and distributed metal domains for efficient charge carrier separation. Furthermore, the effectiveness of semiconductor and semiconductor-metal hybrid gel structures in photocatalytic hydrogen production is demonstrated. Nanoparticles embedded in hydrogels facilitate efficient photocatalysis, ensuring diffusion within the network without requiring colloidal stability. Platinum as a cocatalyst significantly enhances hydrogen production rates. Moreover, the limiting factors in semiconductor-metal hybrid networks appear to be diffusion within the network or the catalytic reaction itself rather than semiconductor-metal electron transfer. Fine-tuning the distribution of metal domains is crucial for optimizing properties tailored to photocatalytic applications.