Abstract
? 2022 Elsevier B.V.In-decorated PdAu catalysts were synthesized and investigated for the aqueous reduction of nitrate. We first synthesized PdAu nanoparticles (NPs) with varying Pd:Au ratios onto which we deposited In. These In-on-PdAu NPs showed higher activity than In-on-Pd NPs for NO3- (kcat=4.0–7.2 vs 2.7 L/gtotal_(Pd+In)/min) due to electronic and ensemble effects. Au-rich NPs had lower activity (kcat=1.3–1.5 L/gtotal_(Pd+In)/min) due to unfavorable hydrogen and nitrate/nitrite binding energies. In-on-PdAu NPs showed higher N2 selectivity than In-on-Pd NPs (90 +% vs 60% at 40% conversion), and had higher activity for NO2-. Density functional theory calculations suggest that Au weakens metal-N bonding which enables nitrite reduction over Pd. Nitrate reduction is promoted by greater mobility of H-adatoms to regenerate InOx and faster spillover of nitrite onto PdAu. When challenged with species found in drinking water, the trimetallic NPs were more active than bimetallic NPs (1.0–1.6 vs 0.6 L/gtotal_(Pd+In)/min). These results expand the prospects of practical catalytic denitrification.
NSTL
Elsevier