Fig 1

Catalytic activities of (a) nCu/γ-Al2O3 and (b) Cu/x%Ga-γ-Al2O3, (c) the effect of temperature on Cu/7.5%Ga-γ-Al2O3, (d) the effect of pressure on Cu/7.5%Ga-γ-Al2O3, and (e) the stability test for Cu/7.5%Ga-γ-Al2O3. The standard reaction conditions: 240 ℃, 3.0 MPa, 3000 mL·g−1·h−1, n(H2)/n(CO2) = 4"

Fig 2

XRD patterns of the (a) nCu/γ-Al2O3 catalysts, (b) Cu/x%Ga-γ-Al2O3 catalysts, and (c) reduced Cu/x%Ga-γ-Al2O3 catalysts."

Fig 3

(a) N2 adsorption-desorption isotherms and (b) pore size distributions of the reduced Cu/x%Ga-γ-Al2O3 catalysts."

Table 1

Textural properties of the reduced Cu/x%Ga-γ-Al2O3 catalysts."

Fig 4

(a) HRTEM image, (b) TEM image, (c) particle size distribution, (d) EDX spectrum, and (e–h) Cu, Al, and O elemental mapping of the reduced Cu/γ-Al2O3 catalyst."

Fig 5

(a) HRTEM image, (b) TEM image, (c) particle size distribution, (d) EDX spectrum, and (e–h) Cu, Al, O, and Ga elemental mapping of the reduced Cu/7.5%Ga-γ-Al2O3 catalyst."

Fig 6

X-ray photoelectron spectroscopy of the reduced Cu/x%Ga-γ-Al2O3 catalysts: (a) Cu 2p, (b) Cu LMM, (c) Al 2p, and (d) Ga 2p."

Table 2

Composition of copper species on the surface of the reduced Cu/x%Ga-γ-Al2O3 catalysts"

Fig 7

(a) H2-TPR profiles of the Cu/x%Ga-γ-Al2O3 catalysts. (b) NH3-TPD profiles and (c) in situ DRIFTS spectra of pyridine adsorbed and desorbed by the reduced Cu/x%Ga-γ-Al2O3 catalysts."

Table 3

Amount of H2 consumed by the Cu/x%Ga-γ-Al2O3 catalysts."

Table 4

Acid contents of the reduced Cu/x%Ga-γ-Al2O3 catalysts."

Fig 8

(a) H2-TPD profiles and (b) CO2-TPD profiles of the reduced Cu/x%Ga-γ-Al2O3 catalysts."

Table 5

Adsorption amounts of H2 and CO2 by the reduced Cu/x%Ga-γ-Al2O3 catalysts."

Fig 9

Charge density difference images of (a) the Cu/γ-Al2O3 interface formed from the Cu10 cluster and the γ-Al2O3 (110) surface and (b) the Cu/Ga-γ-Al2O3 interface formed from the Cu10 cluster and the Ga-doped γ-Al2O3 (110) surface (the blue zone represents electron deficiency, and the yellow zone represents electron enrichment). The planar average CDD along the Z direction of (c) the Cu/γ-Al2O3 interface and (d) the Cu/Ga-γ-Al2O3 interface. Bader charge structure diagrams of (e) the Cu/γ-Al2O3 interface and (f) the Cu/Ga-γ-Al2O3 interface (red: O; orange: Cu; purple: Al; gray: Ga)."

Fig 10

In situ DRIFT spectra of the CO2 hydrogenation reaction on the reduced Cu/7.5%Ga-γ-Al2O3 catalyst. (a) 3100–2650 cm−1, (b) 1800–1250 cm−1. The reaction conditions: 240 ℃, 0.1 MPa, n(H2)/n(CO2) = 4."

Fig 11

Structural evolution of the active sites at the Cu0/Ga-γ-Al2O3 surface interface sites during the CO2 hydrogenation reaction (red: O; orange: Cu; purple: Al; gray: Ga; white: H; black: C)."

Fig 12

Energy profile of CO2 hydrogenation to CH3OH and DME through the HCOO* pathway."

Fig 13

Density of states and -COHP of the 3d orbitals of the interface metal Cu and the 2p orbitals of the adsorbates. (a, b) CO2 on Cu0/γ-Al2O3, (c, d) CO2 on Cu0/Ga-γ-Al2O3, (e, f) HCOO on Cu0/γ-Al2O3, (g, h) HCOO on Cu0/Ga-γ-Al2O3, (i, j) H2COOH on Cu0/γ-Al2O3, (k, l) H2COOH on Cu0/Ga-γ-Al2O3."