Crystal defect engineering of Bi₂Te₃ nanosheets by Ce doping for efficient electrocatalytic nitrogen reduction

Electrochemical nitrogen reduction reaction (NRR) is a promising method for the synthesis of ammonia (NH₃). However, the electrochemical NRR process remains a great challenge in achieving a high NH₃ yield rate and a high Faradaic efficiency (FE) due to the extremely strong N≡N bonds and the competing hydrogen evolution reaction (HER). Recently, bismuth telluride (Bi₂Te₃) with two-dimensional layered structure has been reported as a promising catalyst for N₂ fixation. Herein, to further enhance its NRR activity, a general doping strategy is developed to introduce and modulate the crystal defects of Bi₂Te₃ nanosheets by adjusting the amount of Ce dopant (denoted as Ce_x-Bi₂Te₃, where x represents the designed molar ratio of Ce/Bi). Meanwhile, the crystal defects can be designed and controlled by means of ion substitution and charge compensation. At −0.60 V versus the reversible hydrogen electrode (RHE), Ce_0.3-Bi₂Te₃ exhibits a high NH₃ yield (78.2 μg·h⁻¹·mg_cat⁻¹), a high FE (19.3%), and excellent structural and electrochemical stability. Its outstanding catalytic activity is attributed to the tunable crystal defects by Ce doping. This work not only contributes to enhancing the NRR activity of Bi₂Te₃ nanosheets, but also provides a reliable approach to prepare high-performance electrocatalysts by controlling the type and concentration of crystal defects for artificial N₂ fixation.