TY - JOUR
T1 - Enhanced Stability and Efficiency for Photoelectrochemical Iodide Oxidation by Methyl Termination and Electrochemical Pt Deposition on n-Type Si Microwire Arrays
AU - Ardo, Shane
AU - Santori, Elizabeth A.
AU - Emmer, Hal S.
AU - Grimm, Ronald L.
AU - Bierman, Matthew J.
AU - Brunschwig, Bruce S.
AU - Atwater, Harry A.
AU - Lewis, Nathan S.
N1 - Funding Information:
This work was supported by the National Science Foundation (NSF) Center for Chemical Innovation (CCI) Powering the Planet grants (Grants CHE-0802907, CHE-0947829, and NSF-ACCF) and made use of the Molecular Materials Resource Center of the Beckman Institute at Caltech and the Kavli Nanoscience Institute at Caltech. S.A. acknowledges support from a U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy (EERE) Postdoctoral Research Award under the EERE Fuel Cell Technologies Program.
PY - 2019/9/13
Y1 - 2019/9/13
N2 - Arrays of Si microwires doped n-type (n-Si) and surface-functionalized with methyl groups have been used, with or without deposition of Pt electrocatalysts, to photoelectrochemically oxidize I-(aq) to I3 -(aq) in 7.6 M HI(aq). Under conditions of iodide oxidation, methyl-terminated n-Si microwire arrays exhibited stable short-circuit photocurrents over a time scale of days, albeit with low energy-conversion efficiencies. In contrast, electrochemical deposition of Pt onto methyl-terminated n-Si microwire arrays consistently yielded energy-conversion efficiencies of ∼2% for iodide oxidation, with an open-circuit photovoltage of ∼400 mV and a short-circuit photocurrent density of ∼10 mA cm-2 under 100 mW cm-2 of simulated air mass 1.5G solar illumination. Platinized electrodes were stable for >200 h of continuous operation, with no discernible loss of Si or Pt. Pt deposited using electron-beam evaporation also resulted in stable photoanodic operation of the methyl-terminated n-Si microwire arrays but yielded substantially lower photovoltages than when Pt was deposited electrochemically.
AB - Arrays of Si microwires doped n-type (n-Si) and surface-functionalized with methyl groups have been used, with or without deposition of Pt electrocatalysts, to photoelectrochemically oxidize I-(aq) to I3 -(aq) in 7.6 M HI(aq). Under conditions of iodide oxidation, methyl-terminated n-Si microwire arrays exhibited stable short-circuit photocurrents over a time scale of days, albeit with low energy-conversion efficiencies. In contrast, electrochemical deposition of Pt onto methyl-terminated n-Si microwire arrays consistently yielded energy-conversion efficiencies of ∼2% for iodide oxidation, with an open-circuit photovoltage of ∼400 mV and a short-circuit photocurrent density of ∼10 mA cm-2 under 100 mW cm-2 of simulated air mass 1.5G solar illumination. Platinized electrodes were stable for >200 h of continuous operation, with no discernible loss of Si or Pt. Pt deposited using electron-beam evaporation also resulted in stable photoanodic operation of the methyl-terminated n-Si microwire arrays but yielded substantially lower photovoltages than when Pt was deposited electrochemically.
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U2 - 10.1021/acsenergylett.9b01529
DO - 10.1021/acsenergylett.9b01529
M3 - Article
AN - SCOPUS:85072632526
VL - 4
SP - 2308
EP - 2314
JO - ACS Energy Letters
JF - ACS Energy Letters
SN - 2380-8195
IS - 9
ER -