Nickel-doped ZnO Nanowalls with Enhanced Electron Transport Ability for Electrochemical Water Splitting

This article reports on the growth of 3 mol% nickel (Ni)-doped zinc oxide nanowalls (ZnO NWLs) using the hydrothermal method. Morphological investigation as well as electrical conductivity of the undoped and Ni-doped ZnO NWLs was also discussed. The surface roughness of the formed ZnO NWLs was reduced after Ni-doping. The pore size of Ni-doped ZnO NWLs can be controlled by changing the concentration of hexamethylenetetramine (HMT). As the HMT concentration increased, the pores became larger with increasing surface roughness. The electrical conductivity of the electron-only device based on the Ni-doped ZnO NWLs was higher than that of the undoped one, and it was decreased with increasing the HMT concentration. Our results reveal that Ni-doping and adjustment of the HMT concentration are two key approaches to tune the morphology and electrical properties of ZnO NWLs. Finally, the undoped and Ni-doped ZnO NWLs were used as the catalyst for electrochemical water splitting. The Ni-doped ZnO NWLs with the HMT concentration of 1 mM showed the highest electrochemical performance, which can be attributed to the increased surface area and electrical conductivity.

本文报道了采用水热法制备3摩尔百分比镍（Ni）掺杂氧化锌纳米壁（zinc oxide nanowalls，ZnO NWLs）的生长过程。同时探讨了未掺杂与Ni掺杂ZnO NWLs的形貌表征结果及其导电性能。经Ni掺杂后，所制备ZnO NWLs的表面粗糙度有所降低。六亚甲基四胺（hexamethylenetetramine，HMT）的浓度可调控Ni掺杂ZnO NWLs的孔径尺寸：随着HMT浓度升高，孔径增大且表面粗糙度同步上升。基于Ni掺杂ZnO NWLs的仅电子传输器件的导电性能优于未掺杂样品，且其导电性能随HMT浓度升高而降低。本研究结果表明，Ni掺杂与HMT浓度调控是调控ZnO NWLs形貌与电学性能的两种关键手段。最后，将未掺杂与Ni掺杂ZnO NWLs用作电化学水分解的催化剂。当HMT浓度为1 mM时制备的Ni掺杂ZnO NWLs展现出最优的电化学性能，这可归因于其更大的比表面积与更高的导电性能。