A self-powered system to electrochemically generate ammonia driven by palladium single atom electrocatalyst

The utilization of single atoms (SAs) as trifunctional electrocatalyst for nitrogen reduction, oxygen reduction, and oxygen evolution reactions (NRR, ORR, and OER) is still a formidable challenge. Herein, we devise one-pot synthesized palladium SAs stabilized on nitrogen-doped carbon palladium SA electrocatalyst (Pd-SA/NC) as efficient trifunctional electrocatalyst for NRR, ORR, and OER. Pd-SA/NC performs a robust catalytic activity toward NRR with faradaic efficiency of 22.5% at −0.25 V versus reversible hydrogen electrode (RHE), and the relative Pd utilization efficiency is enhanced by 17-fold than Pd-NP/NC. In addition, the half-wave potential reaches 0.876 V versus RHE, amounting to a 58-time higher mass activity than commercial Pt/C. Moreover, the overpotential at 10 mA cm⁻² is as low as 287 mV for Pd-SA/NC, outperforming the commercial IrO₂ by 360 times in turnover frequency at 1.6 V versus RHE. Accordingly, the assembled rechargeable zinc-air battery (ZAB) achieves a maximum power density of 170 mW cm⁻², boosted by 2.3 times than Pt/C–IrO₂. Two constructed ZABs efficiently power the NRR-OER system to electrochemically generate ammonia implying its superior trifunctionality.