Unconventional phase high-entropy nanoalloys with modulated electronic structure for efficient low-concentration nitrate electroreduction to ammonia

Phase control of alloy nanomaterials can modulate their atomic/electronic structures towards various electrocatalytic applications. However, the controlled synthesis of high-entropy nanoalloys (HENAs) with unconventional phase remains challenging. Here we report the one-pot synthesis of RhCuNiInSb HENAs with the unconventional 2H phase through regulating the nucleation/growth kinetics. Compared with the face-centred cubic phase counterpart, 2H RhCuNiInSb HENAs exhibit superior electrocatalytic nitrate reduction performance at low nitrate concentration. Ex/in situ studies reveal the accelerated deoxygenation/hydrogenation kinetics and distinct reaction pathway. Theoretical calculations demonstrate the electronic optimizations induced by the face-centred-cubic-to-2H phase transition, where the electronic redistribution and p – d elemental interactions improve the surface electroactivity. When operated in flow cell, 0.5 l of simulated wastewater can be efficiently converted into the value-added ammonia-derived product within 10 h. With a 20-h electrolysis, the NO 3 − -N concentration in real industrial and agricultural wastewater can be both reduced above the World Health Organization standard for drinking water.