We discuss recent developments in nanostructured molybdenum sulfide catalysts for the electrochemical hydrogen evolution reaction. To develop a framework for performing consistent and meaningful comparisons between catalysts, we review standard experimental methodologies for measuring catalyst performance and define two metrics used in this perspective for comparing catalyst activity: the turnover frequency, an intrinsic activity metric, and the total electrode activity, a device-oriented activity metric. We discuss general strategies for synthesizing catalysts with improved activity, namely, increasing the number of electrically accessible active sites or increasing the turnover frequency of each site. Then we consider a number of state-of-the-art molybdenum sulfide catalysts, including crystalline MoS 2 , amorphous MoS x , and molecular cluster materials, to highlight these strategies in practice. Comparing these catalysts reveals that most of the molybdenum sulfide catalysts have similar active site turnover frequencies, so the total electrode activity is primarily determined by the number of accessible active sites per geometric electrode area. Emerging strategies to overcome current catalyst limitations and potential applications for molybdenum sulfide catalysts including photoelectrochemical water splitting devices and electrolyzers are also considered.

We demonstrate the translation of a low cost, non-precious metal cobalt phosphide (CoP) catalyst from 1 cm 2 lab-scale experiments to a commercial-scale 86 cm 2 polymer electrolyte membrane (PEM) electrolyser. A 2-step bulk synthesis was adopted to produce CoP on a high surface area carbon support that was readily integrated into an industrial PEM electrolyser fabrication process. The performance of the CoP was compared head-to-head with a platinum-based PEM under the same operating conditions (400 psi, 50 °C). CoP was found to be active and stable, operating at 1.86 A.cm-2 for >1700 hours of continuous hydrogen production while providing substantial material cost savings relative to platinum. This work illustrates a potential pathway for non-precious hydrogen evolution catalysts developed in past decades to translate to commercial applications.

Alloying of Au and Pd leads to new synergistic catalytic effects, providing insights into electrocatalytic CO2 reduction on alloy surfaces.