No abstract

We report, for the first time, the synthesis of the high-quality p-type ZnO NWs using a simple chemical vapor deposition method, where phosphorus pentoxide has been used as the dopant source. Single-crystal phosphorus doped ZnO NWs have their growth axis along the 001 direction and form perfect vertical arrays on a-sapphire. P-type doping was confirmed by photoluminescence measurements at various temperatures and by studying the electrical transport in single NWs field-effect transistors. Comparisons of the low-temperature PL of unintentionally doped ZnO (n-type), as-grown phosphorus-doped ZnO, and annealed phosphorus-doped ZnO NWs show clear differences related to the presence of intragap donor and acceptor states. The electrical transport measurements of phosphorus-doped NW FETs indicate a transition from n-type to p-type conduction upon annealing at high temperature, in good agreement with the PL results. The synthesis of p-type ZnO NWs enables novel complementary ZnO NW devices and opens up enormous opportunities for nanoscale electronics, optoelectronics, and medicines.

No abstract

Water splitting requires nonprecious materials that can catalyze efficiently both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Here, we report the synthesis of mackinawite FeS nanosheets grown on iron foam, which can serve as an efficient pre-electrocatalyst for both HER and OER in alkaline media. During electrochemical HER testing, core@shell iron@iron oxysulfide nanoparticles as the catalytically active phase are generated in situ on FeS nanosheets. During electrochemical OER testing, FeS nanosheets totally transform into porous amorphous FeO x film that can mediate the OER efficiently. When assembled as the cathode and the anode in a single electrolyzer, the resulting Fe-based catalysts can give a good overall watersplitting output that outperforms the one obtained from a noble-metal-based Pt/C-IrO 2-coupled electrolyzer. These results provide new insights on the active sites of Fe-based catalysts as well as an impetus for further research on low-cost, iron-containing water-splitting electrocatalysts.