Probing Local HER Activity in ZrSe 3 Single Nanoribbon Using an On‐Chip Microdevice

ABSTRACT Quasi‐one‐dimensional (1D) crystals naturally expose a high fraction of edges, favorable terminations, and unsaturated coordination sites, especially at ribbon edges, which often bind H* more optimally than basal planes, showing advanced intrinsic catalytic activity. Evaluation of the intrinsic hydrogen evolution reaction (HER) activity of such low‐dimensional electrocatalysts is often hindered by conventional bulk methodologies. On‐Chip Electrocatalytic Microcells (OCEMs) address this limitation by enabling high‐precision measurements at the single‐nanomaterial level. Herein, we report liquid‐phase exfoliation (LPE) to achieve quasi‐1D ZrSe 3 nanoribbons (NRs), and the intrinsic HER activity of individual NRs were investigated using OCEMs for the first time. OCEM measurements on a single ZrSe 3 NR yielded an overpotential of 431 mV at 10 mA cm −2 and a low Tafel slope of 82.3 mV dec −1 , which is vastly superior to the activity obtained using conventional bulk methods, showing 730 mV overpotential and 138 mV dec −1 Tafel slope. Our multi‐scale structure‐property investigation, combining DFT calculations, revealed that the (210) crystallographic facet is more favorable active site over the conventionally expected (001) surface plane. Therefore, these findings demonstrate the potential of OCEMs for evaluating quasi‐1D materials and provide the mechanistic detail needed to advance the rational design of low‐dimensional electrocatalysts based on precise structure‐property relationships.