Controllable Synthesis of Supported PdAu Nanoclusters and Their Electronic Structure-Dependent Catalytic Activity in Selective Dehydrogenation of Formic Acid.

We report the design and synthesis of uniform PdAu alloy nanoclusters immobilized on diamine and graphene oxide-functionalized silica nanospheres. The structure-dependent activity for selectively catalytic dehydrogenation of formic acid (FA) has been evaluated and optimized by controlling the Pd/Au mole ratio and the carrier components. The relationship between the catalyst structure and activity has been investigated via both experiments and characterization. High-resolution transmission electron microscopy (TEM) and X-ray diffraction (XRD) proved the formation of PdAu alloy nanoclusters. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), X-ray photoelectron spectroscopy (XPS), and X-ray absorption fine structure (XAFS) analyses verified the electron transfer between Au, Pd, and the support. An outstanding turnover frequency (TOF) value of 16 647 h-1 at 323 K, which is among the highest activity for FA dehydrogenation ever reported, can be achieved at optimized conditions and ascribed to the combination of the bimetallic synergistic effect and the carrier effect.

Facile Preparation of Porous Carbon Derived from Industrial Biomass Waste as an Efficient CO2 Adsorbent.

A porous carbon CO2 adsorbent based on soybean cake (industrial biomass waste) has been successfully prepared by direct carbonation, following KOH activation. The prepared porous carbon adsorbent exhibits efficient CO2 capture performance with the highest adsorption capacity of 4.19 and 6.61 mmol/g at 298 and 273 K under atmospheric pressure, respectively. Moreover, the porous carbon adsorbent also shows good static CO2 adsorption capacity at a low pressure (0.15 bar) with an uptake of 1.26 mmol/g and an equally ideal dynamic CO2 capture capability with an uptake of 1.28 mmol/g (15% CO2) at 298 K. Additionally, the ideal adsorbed solution theory (IAST) model has been used to measure the selectivity of the porous carbon, and the IAST factors of CO2/N2 (15/85, fuel gas), CO2/CH4 (40/60, biogas), and CH4/N2 (50/50, coalbed gas) are about 27, 6, and 6, respectively. The dynamic breakthrough test reveals the strong interaction between the porous carbon and CO2, which also verifies the considerable selective capture ability of this material for CO2. Furthermore, the soybean cake-based CO2 adsorbent also presents prominent cyclic regeneration capacity (a five-time cyclic test) with lower isosteric heats (34-18 kJ/mmol) of CO2 adsorption.

PtNi/NiO Clusters Coated by Hollow Sillica: Novel Design for Highly Efficient Hydrogen Production from Ammonia-Borane.

Ammonia-borane (NH3·BH3; AB) has been considered as an excellent chemical material for hydrogen storage. However, developing highly efficient catalysts for continuous hydrogen generation from AB is still a challenge for future fuel cell applications. The combination of Pt with Ni is an effective strategy to achieve active bimetallic nanocatalyst, and the particle size has proved to play a crucial role in determining its final activity. However, the synthesis of PtNi bimetallic catalyst in the size of highly dispersed clusters has always been a challenge. In this report, PtNi/NiO clusters coated by small-sized hollow silica (R-PtNi/NiO@SiO2) were designed for efficient hydrogen generation from the hydrolysis of ammonia-borane. The newly designed catalysis system showed extremely high activity with the initial turnover frequency value reaching 1240.3 mol of H2·mol-1 of Pt·min-1, which makes it one the most active Pt-based catalysts for this reaction. Detailed characterization by means of scanning transmission electron microscopy, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy element mapping, etc. revealed that the excellent performance of R-PtNi/NiO@SiO2 is derived from the highly dispersed PtNi/NiO clusters and the reduction of extra Pt4+ on the surface of PtNi/NiO clusters to Pt0 at relatively low temperature.