Electrocatalysis is considered to be one of the most promising and economically feasible future technologies for producing alternative energy sources and plays a major role in the development of solar fuel-based energy conversion schemes. To date, significant efforts are being made to find new, efficient earth-abundant catalytic materials in order to replace the commonly used noble metal based electrocatalysts. In that regard, Metal-Organic Framework (MOF) converted materials have emerged has promising electrocatalysts for these reactions. These MOF-converted high surface-area electrocatalysts exhibit high conductivity and outstanding electrocatalytic activity in several energy conversion and storage applications. Lately, we have developed a means to electrochemically convert MOFs into highly active electrocatalysts (termed EC-MOF). We showed that by controlling the electrochemical parameters of conversion (e.g. scan rate, potential range, number of potential scans) one can precisely manipulate the extent of conversion as well as the chemical composition of the resulting MOF-converted electrocatalysts, and thus subsequently fine-tune their electrochemical hydrogen evolution performance. Yet, further discovery of highly-active electrocatalysts requires the development of new tools for high-throughput synthesis and electrocatalytic screening. As a result, we were interested in designing a method that will allow us to effectively screen the electrocatalytic activity of different MOF-converted catalysts having variable chemical compositions.

Scanning electrochemical microscopy (SECM) is a powerful scanning probe technique for rapid electrochemical activity screening of catalytic materials with varying composition. In this work, we have designed a new method that will allow us to effectively screen the electrocatalytic activity of different MOF-converted catalysts having variable chemical compositions. To do so, we have combined the synthetical and analytical virtues of SECM. In this work we show for the first time that: i) SECM tip electrode could be used to induce spatially-confined (µm-scale) electrochemical conversion of a MOF into patterns of metal sulfides having tuned chemical composition. Thus, we present a facile and simple method to synthesize an array of µm-scale patterned electrocatalysts, toward their activity screening, ii) SECM could be utilized for in-situ HER activity mapping of the as-formed metal sulfide electrocatalysts. Consequently, we provide a proof-of-concept for an SECM-based strategy to synthesize patterned MOF-converted electrocatalysts with tailored composition, coupled with their subsequent in-situ electrocatalytic investigation.