Photocurrent Enhancement of n-Type Cu2O Electrodes Achieved by Controlling Dendritic Branching Growth
- 4 February 2009
- journal article
- research article
- Published by American Chemical Society (ACS) in Journal of the American Chemical Society
- Vol. 131 (7), 2561-2569
- https://doi.org/10.1021/ja806370s
Abstract
Cu2O electrodes composed of dendritic crystals were produced electrochemically using a slightly acidic medium (pH 4.9) containing acetate buffer. The buffer played a key role for stabilizing dendritic branching growth as a pH drop during the synthesis prevents formation of morphologically unstable branches and promotes faceted growth. Dendritic branching growth enabled facile coverage of the substrate with Cu2O while avoiding growth of a thicker Cu2O layer and increasing surface areas. The resulting electrodes showed n-type behavior by generating anodic photocurrent without applying an external bias (zero-bias photocurrent under short-circuit condition) in an Ar-purged 0.02 M K2SO4 solution. The zero-bias photocurrent of crystalline dendritic electrodes was significantly higher than that of the electrodes containing micrometer-size faceted crystals deposited without buffer. In order to enhance photocurrent further a strategy of improving charge-transport properties by increasing dendritic crystal domain size was investigated. Systematic changes in nucleation density and size of the dendritic Cu2O crystals were achieved by altering the deposition potential, Cu2+ concentration, and acetate concentration. Increasing dendritic crystal size consistently resulted in the improvement of photocurrent regardless of the method used to regulate crystal size. The electrode composed of dendritic crystals with the lateral dimension of ca. 12000 μm2 showed more than 20 times higher zero-bias photocurrent than that composed of dendritic crystals with the lateral dimension of ca. 100 μm2. The n-type nature of the Cu2O electrodes prepared by this study were confirmed by linear sweep voltammetry with chopped light and capacitance measurements (i.e., Mott−Schottky plots). The flatband potential in a 0.2 M K2SO4 solution (pH 6) was estimated to be −0.78 vs Ag/AgCl reference electrode. The IPCE measured without applying an external bias was approximately 1% for the visible region. With appropriate doping studies and surface treatment to improve charge transport and interfacial kinetics more efficient n-type Cu2O electrodes will be prepared for use in various photoelectrochemical and photovoltaic devices.Keywords
This publication has 29 references indexed in Scilit:
- Electrodeposited p-type Cu2O for H2 evolution from photoelectrolysis of water under visible light illuminationInternational Journal of Hydrogen Energy, 2008
- Electrochemically constructed p-Cu2O/n-ZnO heterojunction diode for photovoltaic deviceJournal of Physics D: Applied Physics, 2007
- Heterojunction solar cell with 2% efficiency based on a Cu2O substrateApplied Physics Letters, 2006
- Thin film deposition of Cu2O and application for solar cellsSolar Energy, 2006
- Cu2O: a catalyst for the photochemical decomposition of water?Chemical Communications, 1999
- Production of cuprous oxide, a solar cell material, by thermal oxidation and a study of its physical and electrical propertiesSolar Energy Materials and Solar Cells, 1998
- Cu2O as a photocatalyst for overall water splitting under visible light irradiationChemical Communications, 1998
- Cu2O solar cells: A reviewSolar Cells, 1988
- Preparation, characteristics and photovoltaic properties of cuprous oxide—a reviewSolid-State Electronics, 1986
- Experimental and theoretical studies of Cu2O solar cellsSolar Cells, 1982