Carbon-Layer-Protected Cuprous Oxide Nanowire Arrays for Efficient Water Reduction

Abstract

In this work, we propose a solution-based carbon precursor coating and subsequent carbonization strategy to form a thin protective carbon layer on unstable semiconductor nanostructures as a solution to the commonly occurring photocorrosion problem of many semiconductors. A proof-of-concept is provided by using glucose as the carbon precursor to form a protective carbon coating onto cuprous oxide (Cu₂O) nanowire arrays which were synthesized from copper mesh. The carbon-layer-protected Cu₂O nanowire arrays exhibited remarkably improved photostability as well as considerably enhanced photocurrent density. The Cu₂O nanowire arrays coated with a carbon layer of 20 nm thickness were found to give an optimal water splitting performance, producing a photocurrent density of -3.95 mA cm⁻² and an optimal photocathode efficiency of 0.56% under illumination of AM 1.5G (100 mW cm⁻²). This is the highest value ever reported for a Cu₂O-based electrode coated with a metal/co-catalyst-free protective layer. The photostability, measured as the percentage of the photocurrent density at the end of 20 min measurement period relative to that at the beginning of the measurement, improved from 12.6% on the bare, nonprotected Cu₂O nanowire arrays to 80.7% on the continuous carbon coating protected ones, more than a 6-fold increase. We believe that the facile strategy presented in this work is a general approach that can address the stability issue of many nonstable photoelectrodes and thus has the potential to make a meaningful contribution in the general field of energy conversion.

Strongly Coupled Nafion Molecules and Ordered Porous CdS Networks for Enhanced Visible‐Light Photoelectrochemical Hydrogen Evolution

“…[ 26 ] Coating a passivation layer onto the surface of 3D nanostructured photoelectrode is a practical means to reduce the surface trap density which promotes photogenerated charge recombination at the semiconductor/electrolyte interface. [27][28][29] A number of techniques, such as atomic layer deposition (ALD), [ 30 ] spin coating, [ 31 ] electrochemical deposition, [ 3,32 ] sputtering, [ 7 ] and electron beam evaporation [ 7 ] have been developed to coat the passivation layer onto the surface of photoelectrodes. However, in most cases, it is diffi cult to achieve a continuous and conformal passivation layer on 3D surfaces of photoelectrodes, [ 29 ] even by ALD.…”

Hydrogen evolution from a copper(I) oxide photocathode coated with an amorphous molybdenum sulphide catalyst

“…Pt is however too scarce and costly for a largescale application. Thus, there is a growing interest to apply earthabundant and non-precious metal HER catalysts for PEC hydrogen production [11][12][13][14][15][16][17] .…”

Branched nanostructures for photoelectrochemical water splitting

“…Recently, as a solution to the commonly occurring photocorrosion problem of many semiconductors, Zhang and co-workers developed a solution-based carbon precursor coating and subsequent carbonisation strategy to form a thin protective carbon layer on unstable semiconductor nanostructures. 45 Cu 2 O NW arrays coated with a carbon layer of 20-nm thickness gave an optimal water-splitting performance with a photocurrent density of −3·95 mA cm -2 and an optimal photocathode efficiency of 0·56% under illumination of AM 1·5G (100 mW cm -2 ), the highest value ever reported for a Cu 2 O-based electrode without a metal/co-catalyst protective layer. The photostability, measured as the percentage of the photocurrent density at the end of 20-min measurement period relative to that at the beginning of the measurement, showed a more than sixfold increase, improved from 12·6% on the non-protected Cu 2 O NW arrays to 80·7% on the carbon protected ones.…”