Fig. 1. Unreducible-carrier-supported Au NPs and prevailing modification strategies in current research [19-22,27,28].

Fig. 2. Catalytic activity in CO oxidation for the Au0.60Cu0.40/Al2O3 (A) and Au0.60Cu0.40/SiO2 (B) catalysts after an oxidative or reductive pretreatment. Evolution of the Au0.60Cu0.40/Al2O3 catalysts during the in situ XRD (C) and in situ XANES (D) at Cu K-edge during activation (up) and reduction (down), respectively [20].

Fig. 3. Illustration of carbon materials with different dimensions used as inert supports for gold.

Fig. 4. TEM images of Au NPs on activated carbon with extraordinary gold loading and good distribution of Au NPs in Au/C-NC (A) and Au/C-AQ (B); Electro-catalytic selective oxidation of glycerol on Au/C-NC (C) and Au/C-AQ (D) (55 wt%) in AEMDGFC under the optimized condition for a high yield of tartronate [55].

Fig. 5. (A) STEM image of Au/GO before the reaction in fresh status; (B) HRTEM image of an AuNP on GO; (C) HRTEM image of an AuNP on GO after prolonged reduction treatment, with an inset of the fast Fourier transform [66].

Fig. 6. TEM images of Au/H-600 (A), Au/H-800 (B), and Au/TH-800 (C) (H: HAP, -X: calcination temperature in °C); (D) In situ DRIFT spectra of CO adsorption on Au/H-X and Au/H-500-H2; (E) CO conversions at 100 °C on Au/H-500 and Au/H-200 with the alternative treatment of O2 and H2 flow; 40 mg and 50 mg catalysts were used for Au/H-200 and Au/H-500, respectively. Gas flow: 1 vol% CO + 1 vol% O2 balanced with He, 33.3 mL·min-1; (F) In situ DRIFT spectra of CO adsorption on various Au catalysts at room temperature after 10 min adsorption by Au/TH-800 (TH: TiO2 modified HAP); (G) The evolution of in situ DRIFT spectra at -130 °C after introducing 15 torr O2 to the CO preadsorbed Au/TH-800 [67,68].

Fig. 7. (A) Schematic of the Au NPs@OMCs-800 °C obtained from 3D multicomponent colloidal spheres; (B) HAADF-STEM image of Au@OMCs-800 °C; (C,D) elemental mapping images of C, Au, and their overlap in Au@OMCs-800 °C; (E) Conversion of phenylacetylene homocoupling to 1,4-diphenylbutadiyne; (F) conversion of p-nitrobenzene hydrogenation to phenylamine; (G) CV diagrams for different catalysts scanning between the potentials of -0.25 V to 1.0 V with a scan rate of 50 mV·s-1; (H) specific activity of the formic acid oxidation of different catalysts [94].

Fig. 8. (A) CO conversion tendency chart during Au3+ ions loading in the pore channels of HPCN; (B) CO conversion tendency chart with increasing temperature from 20 to 340 °C; (C,D) TEM and STEM images of 7.0 wt% Au/HPCN; (E) schematic explanation of the preparation of a catalyst and catalytic CO oxidation [96].

Fig. 9. (A-D) TEM images and high-magnification TEM image of Au NPs embedded into the ultrathin hollow graphene nanoshell (Au@HGN); (E) STEM and EDX results of the Au@HGN nanocomposite; (F) UV/Vis spectra of 4-nitrophenol reduction reaction in the absence and presence of the Au@HGN catalyst. Inset: color changes of the conversion of 4-nitrophenol to 4-aminophenol; (G) The stability of catalysts under the same reduction reaction with five cycles [97].

Fig. 10. TOF based on p-chloronitrobenzene (p-CNB) and cinnamaldehyde (CAL) as a function of UVO-treatment duration [108].

Fig. 11. Schematic of vapor-assisted ozone functionalization of CNT (A) and schematic of colloidal Au NPs deposited on CNT and oCNT (B), functionalized oCNT under mild (C) and harsh (D) conditions, STEM and HR-TEM images of Au/oCNT after calcination (E,F) [28,118].

Fig. 12. (A) Plot showing the DFT calculated binding energies (in eV) and barriers for auto graphene, oxygenated divacancy (Vac2O2), and oxygenated vacancy (VacO2); (B) Au clusters formed on CNT surfaces after a nominal Au evaporation of 5 ? pristine MWCNTs; (C) Variation of the C 1s and O 1s core levels peak intensity for increasing amounts of Au evaporated onto CNTs- the lines are a visual guide only [128].

Fig. 13. (A) Uv-vis of initial Au colloid and supernatant Au colloid in the presence of SS1 and SS5 with different silica diameters; (B) CO conversion as a function of temperature over different gold catalysts; (C,D) schematic description of the nanostructure variations of different Au catalysts during CO oxidation. The upper inset picture illustrates particle changes during thermal treatment [21,27].

Fig. 14. Comparison of the catalytic activity of CJ-Au/Pd, Au, Pd, and Pd/Au alloy NCs for aerobic glucose oxidation [144]. Schematic insets and numbers shown at the top of each bar indicate the structural models and the average particle sizes, respectively, of the NCs; Au*, the activity was normalized by the number of surface Au atoms in NCs; Pd**, the activity was normalized by the number of surface Pd atoms, the activity of 8290?moles?glucose? h-1?per?mole?surface?Pd.

Fig. 15. (A) Online Pd and Au dissolution profiles recorded with AuPd/C by the SFC/ICP-MS technique during degradation cycle voltammograms; (B) Initial AuPd/C CV (0.1-1.6 VRHE) in Ar-purged 0.1MHClO4 and after degradation protocols; (C) Catalyst EDS line scan after degradation; (D) Representative evolution of the surface composition and the H2O2 selectivity (%) during the ADPs [153].

Fig. 16. (A,B) TEM images of the 3 nm-Au-C observed along the (110) and the (001) directions; FT-EXAFS (C) and XANES (D) spectra for (a) 3.4 and (b) 8.9 nm gold particles on carbon [159].

Fig. 17. (a) Illustration of the nanoparticle formation via the reduction of solvated ions; (b) Pt mass-normalized anodic sweeps obtained from PtAu nanoparticle catalysts in an electrolyte that contained 0.1?M concentrations of both HClO4 and HCOOH, with the peak currents graphed for comparison (left); (c) The plotted FT-EXAFS spectra obtained from Pt and Au L3-edge absorption spectra of PtAu NPs illustrate the drastic under the coordination of Pt atoms in low-Pt-content samples [179].

Fig. 18. (A, B) In situ DRIFT spectra of CuO*/Au sample during CO adsorption and subsequent desorption in He at 25 °C; (C) CO conversion as a function of temperature by different catalysts; (D) The surface composition of Au species revealed by XPS spectra; (E) The relative ratio of CO2 desorption peaks at 100 and 300 °C revealed by CO-TPD [181,182].

Fig. 19. (A) Effects of support water coverage on CO adsorption on Au. The blue region represents water adsorbed onto the support; (B) Schematic representation of the lower (green) pathway [189].