期刊
ACS NANO
卷 7, 期 10, 页码 9407-9415出版社
AMER CHEMICAL SOC
DOI: 10.1021/nn404170y
关键词
branched nanowire (b-NW) heterostructures; photoelectrochemical (PEC) cells; water splitting; oxidation; reduction
类别
资金
- Department of Energy [DOE DE-FG36-08G018016]
- National Science Foundation [NSF ECCS0901113, CBET1236155]
- ONR-DURIP [N00014-08-1-0776]
- National Research Foundation of Korea (NRF)
- Ministry of Science, ICT & Future Planning [R15-2008-006-03002-0]
- Directorate For Engineering
- Div Of Chem, Bioeng, Env, & Transp Sys [1236155] Funding Source: National Science Foundation
- Ministry of Education, Science & Technology (MoST), Republic of Korea [gist-03-06] Funding Source: Korea Institute of Science & Technology Information (KISTI), National Science & Technology Information Service (NTIS)
- Ministry of Science, ICT & Future Planning, Republic of Korea [GIST-03-06] Funding Source: Korea Institute of Science & Technology Information (KISTI), National Science & Technology Information Service (NTIS)
We report the systematic study of 3D ZnO/Si branched nanowire (b-NW) photoelectrodes and their application in solar water splitting. We focus our study on the correlation between the electrode design and structures (including Si NW doping, dimension of the trunk Si and branch ZnO NWs, and b-NW pitch size) and their photoelectrochemical (PEC) performances (efficiency and stability) under neutral conditions. Specifically, we show that for b-NW electrodes with lightly doped p-Si NW core, larger ZnO NW branches and longer Si NW cores give a higher photocathodic current, while for b-NWs with heavily doped p-Si NW trunks smaller ZnO NWs and shorter Si NWs provide a higher photoanodic current. Interestingly, the photocurrent turn-on potential decreases with longer p-Si NW trunks and larger ZnO NW branches resulting in a significant photocathodic turn-on potential shift of 600 mV for the optimized InO/p-Si b-NWs compared to that of the bare p-Si NWs. A photocathode energy conversion efficiency of greater than 2% at -1 V versus Pt counter electrode and in neutral solution is achieved for the optimized ZnO/p-Si b-NW electrodes. The PE( performances or incident photon-to-current efficiency are further improved using Si NW cores with smaller pitch size. The photoelectrode stability is dramatically improved by coating a thin TiO2 protection layer using atomic-layer deposition method. These results provide very useful guidelines in designing photoelectrodes for selective solar water oxidation/reduction and overall spontaneous solar fuel generation using low cost earth-abundant materials for practical clean solar fuel production.
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