Hanfeng Liang

MOF-derived Co-doped nickel selenide/C electrocatalysts supported on Ni foam for overall water splitting

It is of prime importance to develop dual-functional electrocatalysts with good activity for overall water splitting, which remains a great challenge. Herein, we report the synthesis of a Co-doped nickel selenide (a mixture of NiSe2 and Ni3Se4)/C hybrid nanostructure supported on Ni foam using a metal–organic framework as the precursor. The resulting catalyst exhibits excellent catalytic activity toward the oxygen evolution reaction (OER), which only requires an overpotential of 275 mV to drive a current density of 30 mA cm−2. This overpotential is much lower than those reported for precious metal free OER catalysts. The hybrid is also capable of catalyzing the hydrogen evolution reaction (HER) efficiently. A current density of −10 mA cm−2 can be achieved at 90 mV. In addition, such a hybrid nanostructure can achieve 10 and 30 mA cm−2 at potentials of 1.6 and 1.71 V, respectively, along with good durability when functioning as both the cathode and the anode for overall water splitting in basic media.

High performance Na-doped lithium zinc titanate as anode material for Li-ion batteries

A series of Li2−xNaxZnTi3O8 (x = 0, 0.05, 0.10, 0.15, 0.20) are prepared for the first time by a simple solid state method. Upon Na-doping, Rietveld refinement reveals that Na+ takes the 8c tetrahedral sites shared with Li+ and Zn2+ in the structure. Due to the larger ionic radius of Na+ than that of Li+, an increased disorder degree of ion locations in the structure is induced by Na doping. Furthermore, the lithium ion diffusion tunnel is also expanded after Na doping. Thus, higher lithium ion diffusion coefficient can be observed for all the Na-doped Li2ZnTi3O8 samples. However, phase analysis shows that high Na-doping content can result in the formation of impurity in the as-obtained titanates. Besides, the existence of too many Na ions in the spinel also decreases the structural stability. Therefore, Na-doping with low dose is beneficial to improve the electrochemical performance of Li2ZnTi3O8. Electrochemical evaluations show that Li1.95Na0.05ZnTi3O8 has the best lithium storage property among all the Li2−xNaxZnTi3O8. It can be found that Li1.95Na0.05ZnTi3O8 can deliver a reversible capacity of 267.3 mA h g−1 after 50 cycles. This finding can provide an experimental support to synthesize high performance Ti-based materials by Na doping.

Synthesis of 2D hollow hematite microplatelets with tuneable porosity and their comparative photocatalytic activities

α-Fe2O3 2D hollow microplatelets were synthesized by a facile one-pot template-free solvothermal method. The effect of synthetic parameters on the morphology and structure of the product was systematically studied. And the possible formation mechanism was proposed. Interestingly, by simply varying the concentration of NH4F, α-Fe2O3 hollow microstructures with similar platelet-like shapes but different porosities can be readily obtained. Their comparative photocatalytic activities were also investigated.

Facile synthesis of hematite nanostructures with controlled hollowness and porosity and their comparative photocatalytic activities

Hematite nanostructures with similar spindle-like shapes but different hollowness and porosities have been prepared by a facile hydrothermal method. The comparative photocatalytic activities of these samples were investigated and the results might be helpful to further understand the beneficial effects of hollow and porous structures.