Fe-Bi dual sites regulation of Bi2O2.33 nanosheets to promote photocatalytic nitrogen fixation activity

Abstract

In the process of photocatalytic ammonia synthesis, efficient activation of nitrogen molecules constitutes a fundamental challenge. During the N₂ activation, the close interdependence between the acceptance and donation of electron results in their mutual limitation, leading to high energy barrier for N₂ activation and unsatisfactory photocatalytic performance. This work decoupled the electron acceptance and donation processes by constructing Fe-Bi dual active sites, resulting in enhancing N₂ activation through the high electron trapping ability of Fe³⁺ and strong electron donating ability of Bi²⁺. The photocatalytic nitrogen reduction efficiency of 3%Fe/Bi₂O_2.33 (118.71 μmol g_cat^-1h^-1) is 5.3 times that of Bi₂O_2.33 (22.41 μmol g_cat^-1h^-1). In-situ Fourier transform infrared (In situ FTIR) spectroscopy and density functional theory (DFT) calculations manifest that Fe³⁺-Bi²⁺ dual active sites work together to promote nitrogen adsorption and activation, and the reaction path is more inclined toward alternate hydrogenation path. N₂ adsorption and activation properties are optimized by heteronuclear bimetallic active sites, which offers a new way for the rational design of nitrogen-fixing photocatalysts.

Keywords: Acceptance and donation of electron; Fe(3+)-Bi(2+) dual active sites; Fe/Bi(2)O(2.33); N(2) activation; Photocatalytic nitrogen fixation.