Surface Reconstruction of Cobalt Species on Amorphous Cobalt Silicate-Coated Fluorine-Doped Hematite for Efficient Photoelectrochemical Water Oxidation

• DOI: 10.1021/acsami.1c12597
• Publication Date: 2021-10-05T16:45:26Z
• Authors: Huan Chai; Peng Wang; Tong Wang; Lili Gao; Feng Li; Jun Jin
• Keywords: pepd ); Chemical Sciences not elsewhere classified; excellent oer cocatalyst; detailed investigations reveal; feasible strategy; comprehensive method; 02 engineering and technology; Biochemistry; 75 times higher; cobalt species occurred; work provides; Sociology; Space Science; synergistic effect; pec water splitting; surface reconstruction; Environmental Sciences not elsewhere classified; potential hematite photoanode; onset potential; adsorption free energy; Evolutionary Biology; amorphous cobalt silicate; accelerate oer kinetics; efforts significantly reduced; 660; cobalt species; coated fluorine; Computational Biology; interfacial transfer resistance; carrier density; fluorine doping; doped hematite; water oxidation reaction; water oxidation; oxygen evolution reaction; 3 </ sub; assisted electrophoretic deposition; 2 </ sub; 0210 nano-technology; slow kinetics; Biological Sciences not elsewhere classified

The slow kinetics of photoelectrochemical (PEC) water oxidation reaction is the bottleneck of PEC water splitting. Here, we report a comprehensive method to improve the PEC water oxidation performance of a hematite (α-Fe2O3) photoanode, that is, fluorine doping and an ultrathin amorphous cobalt silicate (Co-Sil) oxygen evolution reaction (OER) cocatalyst by photo-assisted electrophoretic deposition (PEPD). Detailed investigations reveal that fluorine doping can reduce the interfacial transfer resistance of charge and increase the carrier density to improve the conductivity of hematite. Also, simultaneously, the Co-Sil is used as an excellent OER cocatalyst to accelerate OER kinetics. Specifically, surface reconstruction of cobalt species occurred, and its average oxidation state increased significantly, which was more conducive to water oxidation. In addition, the presence of silicate groups could reduce the OOH* adsorption free energy. The synergistic effect of these efforts significantly reduced the onset potential and overpotential and enhanced the charge separation of the α-Fe2O3 photoanode, resulting in an excellent photocurrent density around 2.61 mA cm-2 at 1.23 V vs RHE (4.75 times higher than the primitive α-Fe2O3). This work provides a feasible strategy for the construction and development of a potential hematite photoanode.