Defect-Induced Ce-Doped Bi2WO6 for Efficient Electrocatalytic N2 Reduction.

Electrochemical nitrogen reduction reaction (NRR) is a promising method for synthesizing ammonia (NH3). However, due to the extremely strong N≡N bond and the competing hydrogen evolution reaction (HER), the electrochemical NRR process remains a great challenge in achieving a high NH3 yielding rate and a high Faradaic efficiency (FE). Recently, either Bi-based or W-based catalysts have been used in N2 fixation due to lower HER activity. To further promote N2 activation, we develop a simple protocol to introduce and adjust the crystal defects in the host lattice of Bi2WO6 nanoflowers via adjusting the amount of Ce dopant (denoted as xCe-Bi2WO6, where x represents the designed mole percentage of Ce). At -0.20 V versus the reversible hydrogen electrode (RHE), 10%Ce-Bi2WO6 manifests a high NH3 yielding rate (22.5 μg h-1 mg-1cat.), a high FE (15.9%), and excellent electrochemical and structure durability. Its performance is better than most previously reported Bi-based and W-based electrocatalysts for NRR in aqueous solutions. According to density functional theory (DFT) calculations, the introduction of crystal defects into Bi2WO6 can strengthen the adsorption and activation of N2, thus leading to a significant increase in NRR activity.