Interfacial studies in CNT fibre/TiO$_{2}$ photoelectrodes for efficient H$_{2}$ production

TL;DR

This study demonstrates that TiO₂/CNT hybrid photoanodes, fabricated via atomic layer deposition, significantly enhance hydrogen production efficiency by reducing charge transfer resistance and increasing surface area, compared to planar substrates.

Contribution

The paper introduces a novel TiO₂/CNT hybrid architecture with atomic layer deposition that improves photoelectrochemical H₂ production efficiency through interfacial engineering.

Findings

TiO₂/CNT photoanodes nearly double H₂ production compared to planar TiO₂.

Low interfacial charge transfer resistance of 10 Ω due to Ti-O-C bonding.

Enhanced surface area and reduced charge transport resistance improve performance.

Abstract

An attractive class of materials for photo(electro)chemical reactions are hybrids based on semiconducting metal oxides and nanocarbons (e.g. carbon nanotubes (CNT), graphene), where the nanocarbon acts as a highly-stable conductive scaffold onto which the nanostructured inorganic phase can be immobilised; an architecture that maximises surface area and minimises charge transport/transfer resistance. TiO$_{2}$/CNT photoanodes produced by atomic layer deposition on CNT fabrics are shown to be efficient for H$_{2}$ production ($0.07 \mu mol/min$ $H_{2}$ at $0.2V$ $vs Ag/AgCl$), nearly doubling the performance of TiO$_{2}$ deposited on planar substrates, with $100 \%$ Faradaic efficiency. The results are rationalised based on electrochemical impedance spectroscopy measurements showing a large reduction in photoelectron transport resistance compared to control samples and a higher surface area. The low TiO$_{2}$/CNT interfacial charge transfer resistance ($10 \Omega$) is consistent with the presence of an interfacial Ti-O-C bond and corresponding electronic hybridisation determined by spatially-resolved Scanning Photoelectron Microscopy (SPEM) using synchrotron radiation.