Nitrate Electroreduction to Ammonia Coupled with Glucose Electrooxidation Enabled by a Layered Double Hydroxide Tandem Electrocatalyst

The nitrate electroreduction reaction (NO3–RR) represents an effective strategy for the production of high value-added platform chemical ammonia. However, the absence of appropriate tandem electrocatalysts for the NO3–RR limits further development. Here, we report a ternary FeNiCu layered double-hydroxide (LDH) nanosheet catalyst with multiple active sites grown on nickel foam (FeNiCu-LDH/NF) for efficient electroreduction of nitrate sources into ammonia. The FeNiCu-LDH/NF shows high activity for the NO3–RR, resulting in low potentials of 0.328 and 0.247 V vs RHE at 10 and 100 mA cm–2, respectively. It is experimentally and theoretically demonstrated that the multiple active sites of FeNiCu-LDH/NF efficiently catalyze the NO3–RR in tandem. The Cu top site boosts the reduction of *NO3 to *NO2, the Fe–Ni bridge site promotes the reduction of *NO2 to *N, and then the Fe–Cu–Ni hollow site accelerates the hydrogenation of *N to *NH3. Moreover, using FeNiCu-LDH/NF as a bifunctional catalyst, a coupled system of the NO3–RR with the glucose electrooxidation reaction can produce ammonia at the cathode and glucaric acid at the anode with a low voltage of 1.34 V to achieve an electrolytic current density of 100 mA cm–2. This work provides a low-carbon and environmentally friendly path for upgrading chemicals to high value-added products.