In situ electrochemical reduction-assisted exfoliation: conversion of BiOCl nanoplates into Bi nanosheets enables efficient electrocatalytic nitrogen fixation

Abstract

The electrocatalytic nitrogen reduction reaction (NRR) for ammonia (NH₃) synthesis is highly desirable yet still challenging. Catalysts, as the core component of electrocatalytic NRR systems, are a specific focus of research. In this work, we demonstrate that NRR active semimetal bismuth (Bi) ultrathin nanosheets (Bi NSs) could be prepared by means of the in situ electrochemical reduction-assisted exfoliation of BiOCl nanoplates (BiOCl NPs). Such a conversion, from semiconductive BiOCl NPs to semimetal Bi NSs, could create enlarged surface areas and bring about abundant under-coordinated Bi sites and accelerated electron transport capability. With these advantageous properties, the as-converted Bi NSs exhibit efficient NRR electrocatalytic activity in 0.1 M Na₂SO₄, achieving a high faradaic efficiency (14.14%) and NH₃ yield (11.11 μg h⁻¹ mg_cat.⁻¹) at −0.5 V (vs. reversible hydrogen electrode), as well as high NH₃ selectivity.