No abstract

HT) with different Ni/Zn ratios have been prepared by a coprecipitation method. The properties and microstructure of Ni/Zn/Al-HT precursors and derived catalysts were characterized by X-ray diffraction (XRD), H 2 -temperature programmed reduction (TPR), N 2 physical adsorption analysis (BET), scanning electron microscopy (SEM) and particle size distribution. The results exhibited that the as-prepared samples consisted of a hydrotalcite phase and a ZnO phase, and Zn 2+ was introduced into the layers. At the ratio of Ni/Zn ¼ 1, the ZnAl 2 O 4 phase emerged after calcination; Ni still remained in its original state after reaction, and ZnO always existed during the whole process. In aqueous-phase reforming (APR) of ethylene glycol, the H 2 production rate over Ni/Zn/Al-HT was high, and the selectivity of H 2 can almost reach 100% with a high conversion rate exceeding 99%.

Mn3O4 nanoparticles encapsulated inside carbon nanospheres supported on a carbon plate (Mn3O4@CS/CP) were designed, their bifunctional electrocatalytic performance for both, the oxygen evolution reaction (OER) at the anode and the oxygen reduction reaction (ORR) at the cathode were studied in alkaline solution. The prepared Mn3O4@CS/CP catalyst exhibits excellent electrocatalytic performance towards ORR, with less negative onset potential and long durability. Combining the results of in‐situ Fourier transform infrared spectroscopy (FTIR) and density functional theory (DFT) calculations, it is revealed that Mn3O4 acts as active site for ORR to promote the transformation of OH* into OH−. In addition, Mn3O4@CS/CP possesses an excellent electrochemical OER performances with the lower overpotential along with prosper Tafel slope and robust durability. DFT calculations show the transformation from O* to OOH* is the rate determining step for OER, and Mn3O4@CS/CP shows the minimum barrier, indicating that graphene sheet on the outer of Mn3O4 improves the transformation from O* to OOH*. The oxygen electrode activity parameter (potential difference between OER at current density of 10 mA/cm2 and ORR at current density of −2 mA/cm2) on Mn3O4@CS/CP is 0.72 V, which is superior to those of most bifunctional electrocatalysts reported to date, predicting a promising application in metal‐air batteries and fuel cells.