Engineering the surface chemical microenvironment over CuO nanowire arrays by polyaniline modification for efficient ammonia electrosynthesis from nitrate

Electrochemical nitrate reduction into ammonia offers an attractive alternative to value-added ammonia (NH 3 ) production under benign conditions. The critical to achieve satisfactory NH 3 production rate from nitrate electroreduction that can compare with industrial Haber–Bosch route is the development of highly efficient electrocatalysts. In this work, we descript a post-modification strategy for synthesizing polyaniline (PANI)-modified CuO nanowire arrays (CuO@PANI) for selective electrocatalytic nitrate-to-ammonia transformation. Surface modification of CuO with PANI can not only well-retain the nanowire array structure and large specific surface area, but also modulate the surface chemical microenvironment of catalyst, which promotes nitrate enrichment and hydrogenated species accumulation, and thus facilitates selective nitrate-to-ammonia transformation. As a result, the CuO@PANI exhibits high Faradaic efficiency (93.88%) and excellent NH 3 selectivity (91.38%) for NH 3 electrosynthesis from nitrate. The strategy is worthy for designing high-efficiency electrocatalysts by surface modification with organic molecular or polymers for selective nitrate reduction into ammonia. • The CuO@PANI nanowire arrays were synthesized by a post-modification strategy. • The surface chemical microenvironment of CuO was modulated by PANI modification. • PANI promoted enrichment of nitrate and hydrogenated species on catalytic surface. • PANI improved the conductivity of the catalyst and accelerates electron transfer. • The CuO@PANI exhibited high NH 3 selectivity and FE for NH 3 synthesis from nitrate.