Battery-Driven N 2 Electrolysis Enabled by High-Entropy Catalysts: From Theoretical Prediction to Prototype Model.

A small-scale standalone device of nitrogen (N 2 ) splitting holds great promise for producing ammonia (NH 3 ) in a decentralized manner as the compensation or replacement of centralized Haber-Bosch process. However, the design of such a device has been impeded by sluggish kinetics of its half reactions, i.e., cathodic N 2 reduction reaction (NRR) and anodic oxygen evolution reaction (OER). Here, it is predicted from density function theory that high-entropy oxides (HEOs) are potential catalysts for promoting NRR and OER, and subsequently develop a facile procedure to synthesize HEOs in the morphology of sea urchin-shaped hollow nanospheres assembled from ultrathin nanosheets. The excellent electrocatalytic activities of HEOs for both NRR (NH 3 yield rate: 47.58 µg h -1 mg -1 and Faradaic efficiency (FE): 10.74%) and OER (215 mV @10 mA cm -2 ) are demonstrated. Consequently, a prototype device of N 2 electrolysis driven by commercial batteries is constructed, which can operate smoothly and deliver remarkable NH 3 yield rate (41.11 µg h -1 mg -1 ) and FE (14.14%). Further mechanism study has attributed the excellent catalytic performances of HEOs to their unique electronic structures originated from multi-metal synergistic effects and entropy increase effects. The work will provide new clues for designing versatile catalysts and devices for large-scale industrialization.