Tuning Cu/Cu₂O Interfaces for the Reduction of Carbon Dioxide to Methanol in Aqueous Solutions

Abstract

Artificial photosynthesis can be used to store solar energy and reduce CO2 into fuels to potentially alleviate global warming and the energy crisis. Compared to the generation of gaseous products, it remains a great challenge to tune the product distribution of artificial photosynthesis to liquid fuels, such as CH3OH, which are suitable for storage and transport. Herein, we describe the introduction of metallic Cu nanoparticles (NPs) on Cu2O films to change the product distribution from gaseous products on bare Cu2O to predominantly CH3OH by CO2 reduction in aqueous solutions. The specifically designed Cu/Cu2O interfaces balance the binding strengths of H* and CO* intermediates, which play critical roles in CH3OH production. With a TiO2 model photoanode to construct a photoelectrochemical cell, a Cu/Cu2O dark cathode exhibited a Faradaic efficiency of up to 53.6 % for CH3OH production. This work demonstrates the feasibility and mechanism of interface engineering to enhance the CH3OH production from CO2 reduction in aqueous electrolytes.

Facile Synthesis of Sub‐Nanometric Copper Clusters by Double Confinement Enables Selective Reduction of Carbon Dioxide to Methane

“…[21] Thus, the different CO 2 RR performance of the three electrocatalysts correlate to the adsorption strengths of *CO and *H. To this end, we firstly investigated the adsorption ability of *H on the surface of above three electrocatalysts (i.e., DRC, Cu NPs/C, and Cu clusters/DRC) using hydrogen (H 2 ) gas as probe molecules. (Figure 3 a) The temperature-programmed desorption (TPD) of H 2 (H 2 -TPD) for the Cu clusters/DRC showed a board peak at the temperature range of 265-611 8C corresponding to the strong chemisorption of *H intermediates, [22] which can suppress the desorption of *H for formation of H 2 . This can be further verified by the lower HER activity of Cu clusters/ DRC than the other two electrocatalysts.…”

A Disquisition on the Active Sites of Heterogeneous Catalysts for Electrochemical Reduction of CO2 to Value‐Added Chemicals and Fuel

“…Electrocatalytic data from refs. Abbreviations: NW, nanowires; NN, nanoneedles, NPs, nanoparticles; EOD, electrodeposited oxide derived; Air‐LC, low concentration; meso, mesoporous. The detailed catalytic activity of these catalysts is presented in Table S2 (Supporting Information).…”

“…The advantages of OD‐Cu catalysts are also realized through other Cu nanostructures as well, such as mesoporous Cu foam that can generate C 2 H 4 and C 2 H 6 with FE up to 55% at −0.8 V but requires in situ reduction of Cu 2 O phase that is formed during the fabrication process . Likewise, the introduction of metallic Cu nanoparticles on Cu 2 O films was shown to tune the product selectivity from gaseous products to CH 3 OH as the Cu/Cu 2 O interfaces were calculated to balance the binding strength of *H and *CO radical intermediates . As indicated in Figure 9 , the Cu/Cu 2 O interfaces can be tuned by evaporating different mass loadings of Cu on a Cu 2 O layer.…”

“…E1–E5 represents a Cu mass loading of 8.9 × 10 −4 , 1.8 × 10 −3 , 2.7 × 10 −3 , 3.6 × 10 −3 , and 4.5 × 10 −3 mg cm −2 . Reproduced with permission . Copyright 2018, Angewandte Chemie International Edition.…”

“…Schematic of reported active sites in electrocatalysts for CO 2 RR. Reproduced with permission . Copyright 2016, 2019 Wiley‐VCH, Copyright 2014, American Chemical Society, Copyright 2018, Wiley‐VCH, Copyright 2009, Elsevier.…”