期刊
JOURNAL OF PHYSICAL CHEMISTRY C
卷 115, 期 2, 页码 594-598出版社
AMER CHEMICAL SOC
DOI: 10.1021/jp109147p
关键词
-
资金
- Stanford Global Climate and Energy
- U.S. Department of Energy [DE-FG02-05ER15754]
- Kavli Nanoscience Institute
- NSF [CHE-0937048]
- Division Of Chemistry
- Direct For Mathematical & Physical Scien [0937048] Funding Source: National Science Foundation
The effects of introducing an n(+)-doped emitter layer have been evaluated for both planar Si photoelectrodes and for radial junction Si microwire-array photoelectrodes. In contact with the pH-independent, one-electron, outer-sphere, methyl viologen redox system (denoted MV2+/+), both planar and wire array p-Si photoelectrodes yielded open-circuit voltages, V-oc, that varied with the pH of the solution. The highest V-oc values were obtained at pH = 2.9, with V-oc = 0.53 V for planar p-Si electrodes and V-oc = 0.42 V for vapor-liquid-solid catalyzed p-Si microwire array samples, under 60 mW cm(-2) of 808 nm illumination. Increases in the pH of the electrolyte produced a decrease in V-oc by approximately -44 mV/pH unit for planar electrodes, with similar trends observed for the Si microwire array electrodes. In contrast, introduction of a highly doped, n(+) emitter layer produced V-oc = 0.56 V for planar Si electrodes and V-oc = 0.52 V for Si microwire array electrodes, with the photoelectrode properties in each system being essentially independent of pH over six pH units (3 < pH < 9). Hence, formation of an n(+) emitter layer not only produced nearly identical photovoltages for planar and Si microwire array photoelectrodes, but decoupled the band energetics of the semiconductor (and hence the obtainable photovoltage) from the value of the redox potential of the solution. The formation of radial junctions on Si microwire arrays thus provides an approach to obtaining Si-based photoelectrodes with high-photovoltages that can be used for a variety of photoelectrochemical processes, including potentially the hydrogen evolution reaction, under various pH conditions, regardless of the intrinsic barrier height and flat-band properties of the Si/liquid contact.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据