pH-dependent loading of Pt nanoparticles protected by dendrimer in calcium phosphate matrices

Catalytic oxidation of formaldehyde in water by calcium phosphate-based Pt composites

“…With decreasing pH, the particle sizes of the composites and the number of PtNPs in the composites increased. 33 However, the trend in increasing HCHO decomposition from catalyst-pH8 to catalyst-pH12 was inconsistent with the trend in PtNPs content. The reaction was performed using an oxidant, O 2 , in air dissolved in a reaction solution, where different species of catalyst-pHx (x ¼ 12, 8 and 4) were added at a catalyst : HCHO mass ratio of 2 : 1.…”

“…Therefore, the catalytic performance should vary among the catalysts. 33 Consequently, it is obvious that other factors, besides PtNPs content, affect HCHO oxidation. The variable conditions were the PO 4 3À : NH 2 molar ratio in the catalyst-pHx samples and the initial HCHO concentration in the reaction solutions.…”

“…The reaction was performed using an oxidant, O 2 , in air dissolved in a reaction solution, where different species of catalyst-pHx (x ¼ 12, 8 and 4) were added at a catalyst : HCHO mass ratio of 2 : 1. 33 Therefore, the catalytic performance should reect the competing effects of the PtNPs content and the surface area. The HCHO decomposition experiments in Fig.…”

“…33 Typically, an aqueous DENPtNP solution was mixed with an aqueous (NH 4 ) 2 HPO 4 solution and stirred for 3 h. Subsequently, an aqueous Ca(NO 3 ) 2 solution was added with vigorous stirring, and the mixed solutions were adjusted to pH 12, 8, and 4. 31,32 Na 2 PtCl 6 was added to an aqueous DEN solution.…”

“…32 DENPtNPs have also been embedded in mesoporous particles consisting of calcium phosphate (CaP) 33 as an analog of a dendrimer porogen. 32 DENPtNPs have also been embedded in mesoporous particles consisting of calcium phosphate (CaP) 33 as an analog of a dendrimer porogen.…”