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Hydrogen, undoubtedly the next‐generation fuel for supplying the world's energy demands, needs economically scalable bifunctional electrocatalysts for its sustainable production. Non‐noble transition metal‐based electrocatalysts are considered an economic solution for water splitting applications. A single‐step solid‐state approach for the economically scalable transformation of Ni‐based substrates into single‐crystalline nickel sulfide nanoplate arrays is developed. X‐ray diffraction and transmission electron microscopy measurements reveal the influence of the transformation temperature on the crystal growth direction, which in turn can manipulate the chemical state at the catalyst surface. Ni‐based sulfide formed at 450 °C exhibits an enhanced concentration of electrocatalytically‐active Ni3+ at their surface and a reduced electron density around sulfur atoms, optimal for efficient H2 production. The Ni‐based sulfide electrocatalysts display exceptional electrocatalytic performance for both oxygen and hydrogen evolution, with overpotentials of 170 and 90 mV respectively. Remarkably, the two‐electrode cell for overall electrolysis of alkaline water demonstrates an ultra‐low cell potential of 1.46 V at 10 mA cm−2 and 1.69 V at 100 mA cm−2. In addition to the exceptionally low water‐splitting cell voltage, this self‐standing electrocatalyst is of binderfree nature, with the electrode preparation being a low‐cost and single‐step process, easily scalable to industrial scales. [ABSTRACT FROM AUTHOR]

Research groups all over the world are testing new innovative electrodes for batteries aimed at being the next generation of energy‐storage devices. To date, the lab‐scale coin cells, which house two one‐sided electrodes, remain the most common tool to test new battery electrodes. However, many novel electrodes are bilateral by design. In addition, many new electrodes, such as silicon‐ and sulfur‐based, enable large areal capacities that might not be properly tested with any single counter electrode. Here, we suggest a technique to assemble coin cells that incorporate two unilateral electrodes with a bilateral electrode sandwiched between them. This method requires no unique equipment, and can help laboratories with limited resources to test their electrodes under realistic conditions that can better display the capabilities of their research products. [ABSTRACT FROM AUTHOR]