PdAg Nanoparticles within Core-Shell Structured Zeolitic Imidazolate Framework as a Dual Catalyst for Formic Acid-based Hydrogen Storage/Production

Abstract

Formic acid (FA; HCOOH) is one of the most promising candidates for the storage of hydrogen (H2). Herein, we report a H2 storage/production system based on the hydrogenation of CO2 and dehydrogenation of FA, using a nanostructured heterogeneous catalyst. Pd1Ag2 nanoparticles with an average size of 2.8 nm were encapsulated within a zeolitic imidazolate framework (ZIF-8) having a core-shell structure (ZIF-8@Pd1Ag2@ZIF-8). This composite displayed high activity and stability during both the hydrogenation of CO2 to produce FA and the dehydrogenation of FA into H2 and CO2. This improved performance is attributed to the use of ultrafine Pd1Ag2 nanoparticles as well as the spatial regulation of the nanoparticles within the reaction field. This study suggests a new strategy for controlling the spatial distribution of metal nanoparticles within MOFs so as to fine-tune the catalytic activity and selectivity of ZIF-8@metal nanoparticles@ZIF-8 catalysts.

Heterogeneous catalysts for CO2hydrogenation to formic acid/formate: from nanoscale to single atom

“…In an effort to improve the durability of PdAg catalyst, Wen and co-workers encapsulated PdAg nanoparticles into a zeolitic imidazolate framework (ZIF-8) affording a core-shell structure to suppress the aggregation of PdAg nanoparticles (ZIF-8@PdAg@ZIF-8). 123 The spatially-confined PdAg alloy nanoparticles showed an improved stability with a nearly unchanged TON of around 1191 in 24 h for three consecutive activity tests (Table 2, entry 41). In another work, the group of Yamashita reported the encapsulation of PdAg nanoparticles along with branched polyethylenimine (PEI) into a hollow mesoporous organosilica sphere (HMOS) as a bifunctional catalyst to activate both CO 2 and H 2 .…”

MWCNT-Supported PVP-Capped Pd Nanoparticles as Efficient Catalysts for the Dehydrogenation of Formic Acid

“…Nevertheless, such trend was not consistent with that displayed by PVP-free catalysts, since Pd/MWCNT(t), with the largest average nanoparticle size among investigated (4.0 nm), presented the best activity within PVP-free set of catalysts, suggesting that the size of the nanoparticles is not the main factor in governing the catalytic performance of the systems under investigation. Concerning the electronic properties of the nanoparticles, several investigations have reported on the positive effect of electronrich Pd species in catalyzing the decomposition of FA, which has been particularly emphasized by using Pd-based alloyed nanoparticles (Mori et al, 2013;Navlani-García et al, 2016c;Wen et al, 2019). In the present study, the larger relative proportion of Pd(0) in Pd/MWCNT might be related to the better performance displayed by that catalyst as compared to Pd/Vulcan and Pd/CB.…”

Photoreduction of Carbon Dioxide to Formic Acid with Fe-Based MOFs: The Promotional Effects of Heteroatom Doping and Alloy Nanoparticle Confinement

“…Colloidal PdAu nanoparticles in DMF solution were synthesized according to a reported method using HAuCl 4 ·4H 2 O and Pd­(CH 3 COOH) 2 as metal sources and polyvinylpyrrolidone (PVP, 30 K) as a stabilizing agent . To this solution (16.5 mL), [Fe 3 (μ 3 -O)­(CH 3 COO) 6 ] clusters (0.3 g), 2-aminoterephthalic acid (0.3 g), DMF (43.5 mL), and acetic acid (10.5 mL) were added, and the mixture was sonicated to fully dissolve the solids.…”