Enzyme Mimetic Active Intermediates for Nitrate Reduction in Neutral Aqueous Media

Abstract

Nitrate is a pervasive aquatic contaminant of global environmental concern. In nature, the most effective nitrate reduction reaction (NRR) is catalyzed by nitrate reductase enzymes at neutral pH, using a highly‐conserved Mo center ligated mainly by oxo and thiolate groups. Mo‐based NRR catalysts mostly function in organic solvents with a low water stability. Recently, an oxo‐containing molybdenum sulfide nanoparticle that serves as an NRR catalyst at neutral pH was first reported. Herein, in a nanoparticle‐catalyzed NRR system a pentavalent MoV(=O)S4 species, an enzyme mimetic, served as an active intermediate for the NRR. Potentiometric titration analysis revealed that a redox synergy among MoV−S, S radicals, and MoV(=O)S4 likely play a key role in stabilizing MoV(=O)S4, showing the importance of secondary interactions in facilitating NRR. The first identification and characterization of an oxo‐ and thiolate‐ligated Mo intermediates pave the way to the molecular design of efficient enzyme mimetic NRR catalysts in aqueous solution.

Atomic-scale evidence for highly selective electrocatalytic N−N coupling on metallic MoS 2

“…Synthesis and Characterization of MoS 2 . oxo-MoS x was synthesized hydrothermally according to a previously reported procedure (35,36). Briefly, equimolar amounts of molybdate and L-cysteine were mixed and heated inside a Teflon-lined autoclave at 200°C for 24 h.…”

Recent advances in electrocatalytic nitrite reduction

“…According to Fig. 4a, the addition of dithionite (S 2 O 4 − ), which acted as the reductant to activate the catalyst, 48,49 increased the intensity of the electron paramagnetic resonance (EPR) signals assigned to axial signals from Mo( v ) oxo species. The pH-dependent formation of a thiol moiety was observed by operando Raman spectroscopy (Fig.…”

Efficient Nitrogen Fixation to Ammonia through Integration of Plasma Oxidation with Electrocatalytic Reduction

“…1.2 V) to obtain practically acceptable yields and FEs.T his can be ascribed to the low binding affinity and nucleophilicity of NO x À on Cu surface,a nd sluggish water dissociation failing to provide sufficient protons. [14] In contrast, Ni is reported to have strong adsorption of intermediates such as *NO 3 À ,* NO 2 À and *NH 2 . [15] However,H ER activity on Ni surface is too strong, leading to low selectivity and efficiency for ammonia production.…”