Electrical Pulse Induced One-step Formation of Atomically Dispersed Pt on Oxide Clusters for Ultra-Low-Temperature Zinc-Air Battery

Atomically dispersed sites anchored on small oxide clusters are attractive new catalytic materials. Herein, we demonstrate an electrical pulse approach to synthesize atomically dispersed Pt on various oxide clusters in one step with nitrogen-doped carbon as the support (Pt₁ -MO_x /CN). As a proof-of-concept application, Pt₁ -FeO_x /CN is shown to exhibit high activity for oxygen reduction reaction (ORR) with a half-wave potential of 0.94 V vs RHE, in contrast to the poor catalytic performance of atomically dispersed Pt on large Fe₂ O₃ nanoparticles. Our work has revealed that, by tuning the size of the iron oxide down to the cluster regime, an optimal OH* adsorption strength for ORR is achieved on Pt₁ -FeO_x /CN due to the regulation of Pt-O bonds. The unique structure and high catalytic performance of Pt₁ -FeO_x /CN enable the Zinc-Air batteries an excellent performance at ultralow temperature of -40 °C with a high peak power density of 45.1 mW cm^-2 and remarkable cycling stability up to 120 h.

Synergistic Effect of Redox Dual PdO x /MnO x Cocatalysts on the Enhanced H2 Production Potential of a SnS/α-Fe2O3 Heterojunction via Ethanol Photoreforming

In the quest for optimal H₂ evolution (HE) through ethanol photoreforming, a dual cocatalyst-modified heterocatalyst strategy is utilized. Tin(II) sulfide (SnS) was hybridized with α-Fe₂O₃ to form the heterocatalyst FeOSnS with a p-n heterojunction structure as confirmed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV-vis diffusive reflectance spectroscopy (UV-vis DRS), and Brunauer-Emmett-Teller (BET) techniques. PdO _x and PdO _x /MnO _x cocatalysts were loaded onto the FeOSnS heterocatalyst through the impregnation method, as verified by high-resolution transform electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and elemental mapping. Photocatalytic ethanol photoreforming resulted in the production of H₂ as the main product with a selectivity of 99% and some trace amounts of CH₄. The FeOSnS2-PdO _x 2%/MnO _x 1% photocatalyst achieved the highest HE rate of 1654 μmol/g, attributed to the synergistic redox contribution of the PdO _x and MnO _x species.

Comparision on the Low-Temperature NH3-SCR Performance of γ-Fe2O3 Catalysts Prepared by Two Different Methods

Maghemite (γ-Fe2O3) catalysts were prepared by two different methods, and their activities and selectivities for selective catalytic reduction of NO with NH3 were investigated. The methods of X-ray powder diffraction (XRD), Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS), hydrogen temperature-programmed reduction (H2-TPR), ammonia temperature-programmed desorption (NH3-TPD), transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDS), and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) were used to characterize the catalysts. The resulted demonstrated that the γ-Fe2O3 nanoparticles prepared by the facile method (γ-Fe2O3–FM) not only exhibited better NH3-SCR activity and selectivity than the catalyst prepared by the coprecipitation method but also showed improved SO2 tolerance. This superior NH3-SCR performance was credited to the existence of the larger surface area, better pore structure, a high concentration of lattice oxygen and surface-adsorbed oxygen, good reducibility, a lot of acid sites, lower activation energy, adsorption of the reactants, and the existence of unstable nitrates on the surface of the γ-Fe2O3–FM.