Investigating the Effect of the Initial Valence States of Copper on CO₂ Electroreduction

Abstract

The valence states of copper always play an important role for the most studied copper‐based catalysts in CO2 electroreduction (CO2ERR). In this work, distinct Cu, Cu2O, and CuO nanoparticles with similar particle size on active carbon are synthesized via carbonthermal reduction. Although all CuOx nanoparticles are reduced to metallic Cu during CO2ERR, their different initial valence states result in particle‐size variations and different CO2ERR performances. Cu nanoparticles in Cu/C evolve into smaller particles, while those derived from Cu2O/C and CuO/C agglomerate into larger ones. The optimal CO production potential of CO drops with decreasing particle size and is as low as −0.7 V (vs. the eversible hydrogen electrode) on Cu/C. Furthermore, Cu nanoparticles in Cu/C expose much more active sites with higher electrochemical active area and stronger CO adsorption, which further promote C−C coupling to produce C2+ products while inhibiting competitive hydrogen evolution.

Phosphate-Derived Copper-Based Catalysts for Efficient CO2 Reduction to Multicarbon Products

“…As shown in Figure a, the obtained CuO x /C precursors exhibited the morphology feature as nanoparticles deposited on the amorphous active carbon support. Figure a displayed the XRD patterns of CuO x /C precursors, which were consistent with those of Cu [Joint Committee on Powder Diffraction Standards (JCPDS) number 04-0836], Cu 2 O (JCPDS number 65-3288), and CuO (JCPDS number 48-1548), respectively, indicating the composition of Cu/C, Cu 2 O/C, and CuO/C for these CuO x /C precursors . Besides, the broad peaks at around 25° and 44° belonged to the active carbon support.…”

“…As shown in Figure , the phosphate-derived Cu-based catalysts (PD-CuO x /C) were fabricated from the impregnation and calcination of Cu­(NO 3 ) 2 /C to obtain CuO x /C precursors as well as the subsequential PBS treatment and electroreduction of these CuO x /C precursors. , …”

“…CO is believed to be the key intermediate for CO 2 ERR to form C 2+ products; therefore, the reconstructed Cu nanoparticles in PD-CuO x /C not only facilitated the CO formation but also promoted CO dimerization kinetics for C 2+ production. 34 Oxide-derived Cu catalysts are commonly believed to have more exposed defects and grain boundary via the in situ reconstruction process to exhibit better CO 2 ERR performance with preferable C 2+ production compared to non-oxide-derived Cu catalysts. 58−60 In this work, the phosphate-derived Cubased catalysts also exhibited a facilitated C 2+ production ability for CO 2 ERR, which may originate from the highly dispersed Cu nanoparticles in PD-CuO x /C as well as the function of absorbed phosphorus residues, which were formed via the reconstruction of NaPBS treatment and following electroreduction.…”

“…In this work, we report phosphate-derived copper-based catalysts (PD-CuO x /C) for efficient CO 2 ERR toward C 2+ production synthesized via in situ reconstruction. To mitigate the morphology and particle size interference, the highly dispersed copper-based catalysts (CuO x /C) 34 are prepared to investigate the in situ reconstruction function of copper phosphate on the CO 2 ERR performance. Both the morphology and structure evolutions of samples during the in situ reconstruction procedures and the CO 2 ERR performance of PD-CuO x /C samples were investigated.…”

“…In brief, the phosphate-derived Cu-based catalysts (PD-CuO x /C) were fabricated from the impregnation and calcination of Cu(NO 3 ) 2 /C to obtain CuO x /C precursors as well as the subsequent PBS treatment and electroreduction of these CuO x /C precursors. 34,35 First, CuO x /C precursors were synthesized via impregnation and calcination of Cu(NO 3 ) 2 /C. To be specific, 70 mg of Cu(NO 3 ) 2 • 3H 2 O was dissolved in 50 mL of ultrapure water under magnetic stirring, and 200 mg of active carbon was added to the solution.…”