Enhanced Performance of Si MIS Photocathodes Containing Oxide-Coated Nanoparticle Electrocatalysts.
basic_science · Level V
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- Record sourced from PubMed, PMID 27635659.
- Also identified by PMC identifier 7673655.
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Abstract
Electrodepositing low loadings of metallic nanoparticle catalysts onto the surface of semiconducting photoelectrodes is a highly attractive approach for decreasing catalyst costs and minimizing optical losses. However, securely anchoring nanoparticles to the photoelectrode surface can be challenging-especially if the surface is covered by a thin insulating overlayer. Herein, we report on Si-based photocathodes for the hydrogen evolution reaction that overcome this problem through the use of a 2-10 nm thick layer of silicon oxide (SiO<sub>x</sub>) that is deposited on top of Pt nanoparticle catalysts that were first electrodeposited on a 1.5 nm SiO<sub>2</sub>|p-Si(100) absorber layer. Such insulator-metal-insulator-semiconductor (IMIS) photoelectrodes exhibit superior durability and charge transfer properties compared to metal-insulator-semiconductor (MIS) control samples that lacked the secondary SiO<sub>x</sub> overlayer. Systematic investigation of the influence of particle loading, SiO<sub>x</sub> layer thickness, and illumination intensity suggests that the SiO<sub>x</sub> layer possesses moderate conductivity, thereby reducing charge transfer resistance associated with high local tunneling current densities between the p-Si and Pt nanoparticles. Importantly, the IMIS architecture is proven to be a highly effective approach for stabilizing electrocatalytic nanoparticles deposited on insulating overlayers without adversely affecting mass transport of reactant and product species associated with the hydrogen evolution reaction.