Phytate Coordination-Enhanced Electrocatalytic Activity of Copper for Nitroarene Hydrogenation through Concerted Proton-Coupled Electron Transfer

Abstract

Coupling acid−electrolyte proton exchange membrane fuel cells for electricity generation and cathodic hydrogenation for valuable chemical production shows great potential in energy and chemical industry. The key for this promising approach is the identification of cathode electrocatalysts with acid resistance, high activity, and low fabrication cost for practical applications. Among various promising cathodic candidates for this integrative approach, the easily available and cheap Cu suffers from low acidic hydrogenation activity due to kinetically arduous proton adsorption/activation. Inspired by the kinetic advantages of the concerted proton-coupled electron transfer (CPET) over the sequential proton−electron transfer process, herein, we use phytate coordination on Cu surface to overcome the kinetic bottleneck for proton adsorption/activation through the CPET pathway in an acidic half-cell setup; this leads to 1 order of magnitude activity enhancement (36.94-fold) for nitrobenzene hydrogenation. Mechanistic analysis confirms that phytate, as proton acceptor, induces the CPET process and overcomes the above kinetic limitations by tuning the d-band center and concentrating protons on the Cu surface. Consequently, the CPET process facilitates the formation of active hydrogen intermediates for efficient cathodic hydrogenation. This work provides a promising approach to integrate electricity generation and chemical production.

Environment Molecules Boost the Chemoselective Hydrogenation of Nitroarenes on Cobalt Single-Atom Catalysts

“…In previous industrial processes, a conventional way to selectively convert nitroarenes to aniline was using stoichiometric reducing reagents, such as hydrides, sulfur compounds, and reducible metals (Fe, Zn, Sn, and Al) . The underlying origin might relate to the proton transfer (PT) and electron transfer (ET) behaviors during the reduction process (or the so-called E–R model; see Note S3), analogous to Haber’s electrochemical nitro-reduction mechanism . Those PT-ET behaviors are of importance for the reductivity of SAC-derived hydrides, which depend not only on the intrinsic property of the metal but also on the modification of the neighboring structure …”

Developing electrochemical hydrogenation towards industrial application

“…The EChH of organic nitrogen oxides is particularly interesting for the formation of amines with relevance for the pharmaceutic industry with the corresponding nitro-substituted starting materials mostly being easily accessible, especially in the case of aromatic substances. [182][183][184][185][186][187][188][189][190] A dominant current challenge in the EChH of organic nitrogen oxides is associated with the acidic pH that is often required for a relatively efficient conversion, similarly to the EChH of oxygenated compounds. 191 Organic sulfoxides on the other hand are contained as pollutants in fossil fuels so that their economical and easy reduction by electrocatalytic hydrogenation is desirable.…”

Recent progress of Cu-based electrocatalysts for upgrading biomass-derived furanic compounds

“…Based on viable proton and electron transfer pathways, 28 the electrochemical hydrogenation of biomass-derived furans proceeds in two ways. As illustrated in Fig.…”