Highly dispersed Pd-Cu bimetallic nanocatalyst based on γ-Al2O3 combined with electrocatalytic in-situ hydrogen production for nitrate hydroreduction

Bimetallic catalyst exhibits efficient and potential performance for nitrate reduction towards N2 generation. In this work, Pd-Cu bimetallic catalysts are synthesized based on γ-Al2O3 with different loading sequences and annealing temperatures. The characterization of the catalysts with XRD and STEM indicates that the loading methods affect the dispersity of the catalysts. The catalyst obtains much smaller size and more uniform dispersion by first Cu load with annealing at 900 °C and then Pd load (Cu1%(900 °C)-Pd2.5%/γ-Al2O3). The dispersion of Pd and Cu reach 51.81% and 21.93%, respectively. Then the catalysts are applied for nitrate hydroreduction combined with electrocatalytic in-situ hydrogen production using PPy/Ni cathode to obtain high efficiency of H2 utilization and N2 selectivity. For Cu1%(900 °C)-Pd2.5%/γ-Al2O3, the initial reaction rate for N2 generation is 0.70 mg L−1 min−1 and the TOF based on Pd is 2.13 × 10−3 s−1, which is much higher than the others, due to the best dispersion of Pd-Cu on the support. The loading amount is also optimized and the effects of current and pH are investigated to achieve the optimal performance.