Recent Developments in Gold Nanomaterial Catalysts for Oxidation Reaction through Green and Sustainable Routes - Advanced Materials for Agriculture, Food and Environmental Safety - page 215

Table 8.1 Oxidation with mono- and bimetallic catalysts at pH 9.5.
Glucose/Au = 20,000; T = 323 K; reaction time = 2.5 h. Reproduced
with permission fr om [102].

Metals Type of catalyst Conversion % TOF (h -1 )

Au Supported 43 17200

Au-Pt (2:1) Supported 44 17600

Au UnSupported 12 4600

Pt UnSupported <2 <500

Pd UnSupported 5 2000

Au-Pt (2:1) UnSupported 26 10500

Au-Pd (2:1) UnSupported 28 11600

25000

20000

15000

10000

5000

0 0

2 4 6 8 10 12

diameter (nm)

Figure 8.20 Correlation between activity and particle size of unsupported gold
nanoparticles during the aerobic oxidation of glucose. Experimental conditions: [glucose]
= 0.38 M; [Au] = 3.2 × 10 -5 M; glucose : Au = 12 000, T = 303 K, pH = 9.5, pO 2 = 1 bar.
Reproduced with permission from [105].

the diameter of the nanoparticles in the range of 2.5-4.5 nm but a devia-
tion from linearity for particles larger than 6 nm, as well as the inactiveness
for those larger than 10 nm.
h e rapid decrease of activity for particles larger than 6 nm indicates a
discontinuity in the catalytic behavior, which is not only due to geometri-
cal factors, but likely due to electronic factors inl uencing the electrophilic
properties of the particles. By the way, other properties show a sudden