Hydrogen-evolution characteristics of Ni–Mo-coated, radial junction, n+p-silicon microwire array photocathodes
- 8 October 2012
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Energy & Environmental Science
- Vol. 5 (11), 9653-9661
- https://doi.org/10.1039/c2ee23192a
Abstract
The photocathodic H2-evolution performance of Ni–Mo-coated radial n+p junction Si microwire (Si MW) arrays has been evaluated on the basis of thermodynamic energy-conversion efficiency as well as solar cell figures of merit. The Ni–Mo-coated n+p-Si MW electrodes yielded open-circuit photovoltages (Voc) of 0.46 V, short-circuit photocurrent densities (Jsc) of 9.1 mA cm−2, and thermodynamically based energy-conversion efficiencies (η) of 1.9% under simulated 1 Sun illumination. Under nominally the same conditions, the efficiency of the Ni–Mo-coated system was comparable to that of Pt-coated n+p-Si MW array photocathodes (Voc = 0.44 V, Jsc = 13.2 mA cm−2, η = 2.7%). This demonstrates that, at 1 Sun light intensity on high surface area microwire arrays, earth-abundant electrocatalysts can provide performance comparable to noble-metal catalysts for photoelectrochemical hydrogen evolution. The formation of an emitter layer on the microwires yielded significant improvements in the open-circuit voltage of the microwire-array-based photocathodes relative to Si MW arrays that did not have a buried n+p junction. Analysis of the spectral response and light-intensity dependence of these devices allowed for optimization of the catalyst loading and photocurrent density. The microwire arrays were also removed from the substrate to create flexible, hydrogen-evolving membranes that have potential for use in a solar water-splitting device.Keywords
This publication has 25 references indexed in Scilit:
- Wireless Solar Water Splitting Using Silicon-Based Semiconductors and Earth-Abundant CatalystsScience, 2011
- Evaluation of Pt, Ni, and Ni–Mo electrocatalysts for hydrogen evolution on crystalline Si electrodesEnergy & Environmental Science, 2011
- Bioinspired molecular co-catalysts bonded to a silicon photocathode for solar hydrogen evolutionNature Materials, 2011
- Photoelectrochemical Hydrogen Evolution Using Si Microwire ArraysJournal of the American Chemical Society, 2011
- High-performance Si microwire photovoltaicsEnergy & Environmental Science, 2011
- Flexible, Polymer‐Supported, Si Wire Array PhotoelectrodesAdvanced Materials, 2010
- Si microwire-array solar cellsEnergy & Environmental Science, 2010
- Energy-Conversion Properties of Vapor-Liquid-Solid–Grown Silicon Wire-Array PhotocathodesScience, 2010
- Comparison of the device physics principles of planar and radial p-n junction nanorod solar cellsJournal of Applied Physics, 2005
- High-Efficiency Photoelectrochemical Hydrogen Production Using Multijunction Amorphous Silicon PhotoelectrodesEnergy & Fuels, 1998