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Metal Sputtering Buffer Layer for High Performance Si-Based Water Oxidation Photoanode

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journal contribution
posted on 31.08.2020, 21:04 by Chang Zhao, Beidou Guo, Guancai Xie, Chengcheng Li, Wenjing Xie, Yawen Dai, Jinlong Gong, Jian Ru Gong
The sputtering deposition commonly adopted in the photoelectrochemical water splitting device usually causes structure damage and accordingly performance degradation. Taking the Si-based photoanode as a model system, we propose a facile strategy to enable sputtering deposition of the film without damaging the underlying layer by introducing a metal sputtering buffer layer, which ensures high-quality interface structure and excellent water oxidation performance. In our work, the Ni sputtering buffer layer avoids the damage on the Al2O3 passivation layer during the NiFe oxide electrocatalyst sputtering process. Consequently, a Si/Al2O3/Ni metal–insulator–semiconductor junction with a precise configuration is formed, which increases the Si barrier height by reducing the interface state density and suppressing Fermi-level pinning, thus enhancing the photovoltage in thermodynamics and accelerating the oxygen evolution reaction (OER) in kinetics. In addition, the dense NiFe oxide with high transmittance and antireflection properties functions as both an efficient OER electrocatalyst and a robust protective layer and contributes to efficient use of the incident light. The photoanode affords a high water oxidation activity with an onset potential of ∼0.92 V vs reversible hydrogen electrode (VRHE) and a high photocurrent density of ∼31 mA cm–2 at 1.23 VRHE after further incorporating the cocatalyst NiFe-layered double hydroxide and has no obvious decay after 330 h of continuous operation. This strategy is beneficial for developing energy conversion devices on a large scale.