Mesoporous PdN Alloy Nanocubes for Efficient Electrochemical Nitrate Reduction to Ammonia.

Abstract

Developing highly active and selective electrocatalysts for electrochemical nitrate reduction reaction (NITRR) is very important for synthesizing recyclable ammonia (NH3 ) in an economic and environmentally friendly manner. Despite some encouraging progress, their activity and selectivity have been remarkably slower than expected. In this manuscript, mesoporous palladium-nonmetal (meso-PdX) nanocubes (NCs) are reported as a new series of highly efficient electrocatalysts for selective nitrate reduction reaction (NITRR) electrocatalysis to NH3 . The samples feature uniformly alloyed compositions and highly penetrated mesopores with abundant highly active sites and optimized electronic structures. The best meso-PdN NCs hold an outstanding NITRR activity and selectivity with a remarkable NH3 Faradaic efficiency of 96.1% and a yield rate of 3760µg h-1 mg-1 , suppressing the state-of-the-art electrocatalysts. Meanwhile, meso-PdN NCs are electrocatalytically stable, retaining well the activity and selectivity of NO3 - -to-NH3 electrocatalysis for more than 20 cycles. Detailed mechanism studies ascribe the superior performance to combined compositional and structural synergies of meso-PdN NCs that not only promote the adsorption (reactivity) of NO3 - and the desorption of NH3 but also increase the retention time of key intermediates for the deeper NITRR electrocatalysis to NH3 through an eight-electron pathway.