The advancement of hydrogen energy is an urgent necessity for the global energy transition and the realization of carbon neutrality. In water electrolysis, the development of novel catalysts is pivotal, while continued innovation in in situ electrochemical characterization is equally essential. This work presents a high-throughput in situ total internal reflection imaging (TIRi) platform that provides a "one stone, three birds" solution-concurrently enabling visualization of catalyst spatial uniformity, rapid qualitative performance screening, and quantitative evaluation of compositional sets. The system integrates a redesigned optical architecture with a 4 × 4 electrode array, establishing a direct correlation between optical contrast and electrochemical response. Using representative catalysts (Pt/C, NiFe, MoS2, and WS2) patterned on the array, we verify spatial consistency and elucidate activity variations in the hydrogen evolution reaction (HER). Furthermore, a Mo-Ru compositional-gradient alloy was fabricated, through which the optimal composition (Mo:Ru = 1:0.339) was identified, revealing the intrinsic correlation between electrocatalytic performance and compositional ratio. This nondestructive, cost-efficient, and inherently scalable method enables statistically robust, high-throughput catalyst discovery without compromising mechanistic insight, while offering a broadly generalizable operando framework that accelerates the rational design and optimization of electrocatalysts for sustainable energy technologies.
Lin et al. (Fri,) studied this question.