Substantial lifetime enhancement for Si-based photoanodes enabled by amorphous TiO2 coating with improved stoichiometry
Yutao Dong, Mehrdad Abbasi Gharacheh, Jun Meng, Lazarus German, Corey Carlos, Jun Li, Ziyi Zhang, Dane Morgan, Jinwoo Hwang, Xudong Wang
Abstract
Abstract Amorphous titanium dioxide (TiO 2 ) film coating by atomic layer deposition (ALD) is a promising strategy to extend the photoelectrode lifetime to meet the industrial standard for solar fuel generation. To realize this promise, the essential structure-property relationship that dictates the protection lifetime needs to be uncovered. In this work, we reveal that in addition to the imbedded crystalline phase, the presence of residual chlorine (Cl) ligands is detrimental to the silicon (Si) photoanode lifetime. We further demonstrate that post-ALD in-situ water treatment can effectively decouple the ALD reaction completeness from crystallization. The as-processed TiO 2 film has a much lower residual Cl concentration and thus an improved film stoichiometry, while its uniform amorphous phase is well preserved. As a result, the protected Si photoanode exhibits a substantially improved lifetime to ~600 h at a photocurrent density of more than 30 mA/cm 2 . This study demonstrates a significant advancement toward sustainable hydrogen generation.