Efficient Electrocatalytic Nitrate Reduction to Ammonia Based on DNA-Templated Copper Nanoclusters

Abstract

In alkaline solutions, the electrocatalytic conversion of nitrates to ammonia (NH 3 ) (NO 3 RR) is hindered by the sluggish hydrogenation step due to the lack of protons on the electrode surface, making it a grand challenge to synthesize NH 3 at a high rate and selectivity. Herein, single-stranded deoxyribonucleic acid (ssDNA)-templated copper nanoclusters (CuNCs) were synthesized for the electrocatalytic production of NH 3 . Because ssDNA was involved in the optimization of the interfacial water distribution and H-bond network connectivity, the waterelectrolysis-induced proton generation was enhanced on the electrode surface, which facilitated the NO 3 RR kinetics. The activation energy (E a ) and in situ spectroscopy studies adequately demonstrated that the NO 3 RR was exothermic until NH 3 desorption, indicating that, in alkaline media, the NO 3 RR catalyzed by ssDNA-templated CuNCs followed the same reaction path as the NO 3 RR in acidic media. Electrocatalytic tests further verified the efficiency of ssDNA-templated CuNCs, which achieved a high NH 3 yield rate of 2.62 mg h −1 cm −2 and a Faraday efficiency of 96.8% at −0.6 V vs reversible hydrogen electrode. The results of this study lay the foundation for engineering catalyst surface ligands for the electrocatalytic NO 3 RR.

Ligand Design in Atomically Precise Copper Nanoclusters and Their Application in Electrocatalytic Reactions

“…The functional group on the end of ligands can interact with the local microenvironment, resulting in different catalytic behavior. [ 8,45 ] Moreover, the LP‐CuNCs can be widely used in many electrochemical reactions including electrochemical carbon dioxide reduction reaction (CO 2 RR), [ 46–49 ] oxygen reduction reaction (ORR), [ 50–52 ] nitrate reduction reaction (NO 3 RR), [ 53 ] oxygen evolution reaction (OER), [ 54 ] etc., which are in great need of high‐performance catalysts.…”

Ag‐Co3O4‐CoOOH‐Nanowires Tandem Catalyst for Efficient Electrocatalytic Conversion of Nitrate to Ammonia at Low Overpotential via Triple Reactions

“…[ 6,7 ] However, NRR suffers low selectivity and activity due to the highly stable N≡N triple bond (941 kJ mol −1 ) and low water solubility. [ 8,9 ] To cover the shortage, electrocatalytic nitrate (NO 3 ‾) reduction to ammonia (NO 3 RR) is desirable because the NO 3 ‾ exhibits comparatively low dissociation energy of the N═O bond (204 kJ mol −1 ). [ 10,11 ] Also, NO 3 ‾ is widely abundant as pollution in agricultural and industrial wastewater.…”

Balanced NOx– and Proton Adsorption for Efficient Electrocatalytic NOx– to NH3 Conversion

“…Herein, we designed balanced NO x – and proton adsorption on 2.1 at% Cu-doped Fe/Fe 2 O 3 (Cu–Fe/Fe 2 O 3 ) to achieve high FE and yield rate for NH 3 production under low NO x – concentrations. It is understood that weakened hydrogen (H) adsorption may promote the affinity for NO 3 – at the active sites. , However, the excessive suppression of H adsorption could lead to an inadequate supply of *H (where * denotes an adsorbed specie) during the hydrogenation step, resulting in limited NH 3 conversion. − Thus, by properly introducing Cu sites into Fe/Fe 2 O 3 , we effectively strike a balance between H adsorption and favorable NO x – affinity. As a result, the Cu–Fe/Fe 2 O 3 catalyst exhibits promising performance with an average NH 3 FE of ∼98% and an average NH 3 yield rate of 15.66 mg h –1 cm –2 when operating under the NO 3 – concentration (32.3 mM) of typical industrial wastewater and at an applied potential of −0.6 V, exceeding the industrialization targets.…”