Cu2O-based photocathodes as stable and efficient photoelectrochemical energy conversion catalysts require protections due to their photocorrosion at the electrode liquid junction (ELJ). In this presentation, recent progress on the development of stabilized Cu2O-based photocathodes for photoelectrochemical conversion will be introduced. Particularly, pulsing electrodeposition as a scalable protecting technique developed by our group will be presented. Wide bandgap n-type semiconductor films such as TiO2 with ultrathin thickness decorated on top of Cu2O can protect the photocorrosion of the Cu2O from the aqueous electrolyte, thereby ameliorate the performance in favor of solar energy conversion. But, TiO2 grown from titanium tetraisopropoxide and H2O is known to have issues with growing non-uniformly. Herein, a buffer interlayer is crucial to assist the uniform coating of the protecting layer of TiO2 on the Cu2O. Interlayers such as ZnO and Ga2O3 have been deposited between Cu2O and the protective layer of TiO2 by atomic layer deposition to afford the chemical stability. Atomic layer deposition technique is however too complicated the costly for a large scale application. Also, limited semiconductors are available that could conformably deposit by atomic layer deposition. Herein, we developed a pulsing electrodeposition method to introduce an ultrathin interlayer containing ZnOx (ZnO and Zn(OH)2) on the Cu2O layer. In combine with dip-coating of TiO2, the surface-protected Cu2O photoelectrode achieves a higher and more stable photoresponse under visible light illumination. Due to the ultrathin property of the coated overlayers containing ZnOx and TiO2, time-of-flight secondary ion mass spectrometer (TOF-SIMs) was utilized to investigate the composition and chemical state of our designed multilayer photoelectrodes. A systematic investigation of the enhanced visible light-induced charge extraction in protected Cu2O photoelectrodes was also studied by Nyquist and time-resolved photoluminescence (TRPL). The enhanced photocathodic performance demonstrates the great potential of pulsing electrodeposition as a versatile alternative coating technique in addressing the non-stable issue of photoelectrodes for photoelectrochemical conversion.

Pulsed electrodeposition of an ultrathin ZnOx interlayer for stabilizing Cu2O-based photocathodes for photoelectrochemical applications

256th National Meeting (2018)

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