Instant formation of excellent oxygen evolution catalyst film via controlled spray pyrolysis for electrocatalytic and photoelectrochemical water splitting

Abstract

The retarded kinetics of oxygen evolution on electrodes is a bottleneck for electrochemical energy conversion and storage systems. NiFe-based electrocatalysts provide a cost-effective choice to confront this challenge. However, there is a lack of facile techniques for depositing compact catalytic films of high coverage and possessing a state-of-the-art performance, which is especially desired in photoelectrochemical (PEC) systems. Herein, we demonstrate a spray pyrolysis (SP) route to address this issue, featuring the kinetic selective preparation towards the desired catalytic-active material. Differing from reported SP protocols which only produce inactive oxides, this approach directly generates a unique composite film consisting of NiFe layered oxyhydroxides and amorphous oxides, exhibiting an overpotential as small as 255 mV (10 mA cm−2) and a turnover frequency of ∼0.4 s−1 per metal atom. By using such a facile protocol, the surface rate-limiting issue of BiVO4 photoanodes can be effectively resolved, resulting in a charge injection efficiency of over 90%. Considering this deposition directly start from simple nitrates but only takes several seconds to complete, we believe it can be developed as a widely applicable and welcomed functionalization technique for diverse electrochemical devices.