Facet and d-band center engineering of CuNi nanocrystals for efficient nitrate electroreduction to ammonia

Abstract

Electrocatalytic nitrate reduction offers a sustainable route to ammonia synthesis and wastewater treatment. However, the nitrate-to-ammonia conversion remains inefficient due to the sluggish kinetics and diverse side reactions. Herein, well-faceted...

Rags to Riches: Meliorating the Electrocatalytic Reduction of Nitrate to Ammonia over Cu-Based Nanoalloys

“…In fact, the onset potentials were at a slightly lower cathodic potential for pristine Cu/C and Cu 0.85 Ni 0.15 /C compared to Cu 0.85 Zn 0.15 /C, indicating the critical role of monometallic and bimetallic nanoalloy catalysts in the activation of nitrate ions. The first minor peak at about −0.4 V could be due to the reduction of NO 3 – to NO 2 – , whereas the second major peak around −0.75 V was assigned to the reduction of NO 2 – to NH 3 . , Among the materials, the current density of Cu 0.85 Zn 0.15 /C was found to be higher than that of the other two catalysts (particularly at higher potential), implying a higher catalytic NO x RR efficacy over the nanoalloy. But as discussed, the higher current density in the LSV plot may not differentiate well between an HER and NO x RR.…”

“…− to NO 2 − , whereas the second major peak around −0.75 V was assigned to the reduction of NO 2 − to NH 3 . 34,35 Among the materials, the current density of Cu 0.85 Zn 0.15 /C was found to be higher than that of the other two catalysts (particularly at higher potential), implying a higher catalytic NO x RR efficacy over the nanoalloy. But as discussed, the higher current density in the LSV plot may not differentiate well between an HER and NO x RR.…”

Electrodeposited copper–nickel nanoparticles as highly efficient electrocatalysts for nitrate reduction to ammonia

“…46 In addition, Ni holds great promise for H* provision but with suitable HER activity. 47,48 Although Cu–Ni nanocatalysts have been reported so far, 46,49–51 they were prepared through a relatively strenuous method and most electrochemical evaluations were implemented in high-concentration NO 3 − -containing solutions where the HER activity could be circumscribed.…”

“…3e). 42,[49][50][51] The electrochemical test at an open-circuit potential (OCP) by using CuNi/TM-20 as a working electrode was conducted to conrm that the generated NH 3 indeed originates from the NO 3 − RR. As shown in Fig.…”

Mixed-valence Cu-based heterostructures for efficient electrochemical nitrate reduction to ammonia

“…2 Copper (Cu) is regarded as one of the most active metals for the NO 3 RR since it exhibits high current density and superior kinetics for the reduction of nitrate to nitrite. [6][7][8][9][10][11][12] This is attributed to similar d-orbital energy levels of Cu to the lowest unoccupied molecular π* orbital (LUMO π*) of NO 3 − , thereby facilitating electron transfer. 13 Moreover, Cu-based catalysts, with the characters of low cost, high conductivity, and inferior activity for the competing hydrogen evolution reaction (HER), are ideal candidates for the electrochemical NO 3 RR to ammonia.…”