A Highly Active and Robust Copper-Based Electrocatalyst toward Hydrogen Evolution Reaction with Low Overpotential in Neutral Solution

Abstract

Although significant progress has been made recently, copper-based materials have long been considered to be ineffective catalysts toward the hydrogen evolution reaction (HER), in most cases, requiring high overpotentials more than 300 mV. We report here that a Cu(0)-based nanoparticle film electrodeposited in situ from a Cu(II) oxime complex can act as a highly active and robust HER electrocatalyst in neutral phosphate buffer solution. The as-prepared nanoparticle film is of poor crystallization, which incorporates significant amounts of oxime ligand residues and buffer anions PO. The proposed mechanism suggests that the Cu(0)-based nanoparticle film is activated with incorporated or adsorbed PO anions and the PO anions-anchored sites might serve as the actual catalytic active sites with efficient proton transport mediators. Catalysis occurs with a low onset overpotential (η) of 65 mV, and a current density of 1 mA/cm can be achieved with η = 120 mV. The nanoparticle film shows an excellent catalytic durability with slightly rising current density during electrolysis, presumably due to further incorporation or adsorption of PO anions in the process. This electrocatalyst not only forms in situ from earth-abundant materials but also operates in neutral water with low overpotential and high stability.

Bio-inspired design: bulk iron–nickel sulfide allows for efficient solvent-dependent CO2 reduction

“…E.g. Cu and pyrite (FeS 2 ) were both reported to facilitate H 2 generation as well as CO 2 reduction at various conditions and further support the Janus-faced character of both processes 13–17…”

Nanoporous Gold Surface: An Efficient Platform for Hydrogen Evolution Reaction at Very Low Overpotential

“…As a result, enormous efforts have been devoted to finding alternative catalysts for producing hydrogen at low overpotential. For example, cobalt, [11][12][13] nickel, 14 copper [15][16][17] bimetallic catalyst, 18 transition metal carbide nanocrystals M3C (M: Fe, Co, Ni) encapsulated with vertically aligned graphene nanoribbons, 19 nitrogen and sulfur co-doped nanoporous graphene, 20 molybdenum sulfide (MoS 2 ), phosphide, carbon and noble metal-free catalysts are reported for the HER process. [21][22][23][24] Currently, nanoporous gold films (NPGF) have attracted attention for their widespread application in catalysis and in the sensors field because of their higher surface area in comparison to bulk gold electrodes, allowing superior electron transfer rate between the electrode-electrolyte interface.…”

Commercially Available CuO Catalyzed Hydrogenation of Nitroarenes Using Ammonia Borane as a Hydrogen Source

“…[27] All the fresh and used CuO samples were also characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) to investigate the change in their compositions ( Figure 1C, D). After the reaction, the XRD pattern of catalyst can be ascribed to the Cu(0) phase with a cubic structure ( Figure 1C), [40] and the peaks of Cu 2p 3/2 and Cu 2p 1/2 were observed with binding energies located at 932.2 and 951.9 eV ( Figure 1D), [40,41] thus demonstrating that CuO was indeed reduced to Cu(0). On the basis of the above observations, we were able to propose that the reduction of blockshaped CuO powder by ammonia borane would generate the spongy structure with larger surface area consisting of Cu(0) nanoparticles ( Figure 1B), which could significantly increase the number of active sites and catalytic activity ( Table 2).…”

“…This hydrogenation proved to be insensitive towards steric encumbrance in the vicinity of the targeted nitro group (1-4, 6-8). Gratifyingly, the reductions were successfully carried out when reducible functional groups existed in the substrates, including halogens (10)(11)(12)(13)(14)(15), amides (18,19), oximes (23,24), esters (25)(26)(27)(28)(29)(30), alkenyl (29,30), nitriles (40,41), and imines (42), furnishing the desired products in moderate to excellent yields and chemoselectivities. However, nitroarenes substituted with aldehydes or ketones were not tolerated under the standard reaction conditions, owing to the reduction of these functionalities by AB (see Scheme S1 in the Supporting Information), which is consistent with previous reports.…”