Recently, Professor Yong Zhao’s research group has made new progress in the design and construction of multi-stage structure electrolyzed water electrodes with high conductivity and abundant catalytic active sites. The related results are entitled "Hierarchy carbon nanotube forest supported metal phosphide electrode for the efficient overall water splitting". The full text format is published in Journal of Materials Chemistry A (J. Mater. Chem. A 2020, DOI: 10.1039/D0TA10964A).

The catalytic activity of electrodes is not only affected by the intrinsic activity of the catalytic site, but also closely related to the number of active sites and conductivity of electrode. The abundant active sites and excellent conductivity are the core factors of the electrode to achieve its high catalytic activity.

Schematic illustration of catalytic hydrogen evolution/oxygen evolution reaction of multi-stage self-supportive carbon nanotube electrodes coupled with metal phosphides

In this work, Yong Zhao’s group first prepared a self-supportive carbon nanotube network (CNT@NiCo/CP) with hierarchical branched architecture. Employing the above-mentioned self-supportive carbon nanotube as a support, and anchoring metal phosphide nanoparticles with abundant defect sites on the surface of carbon nanotubes (CNTs), and then, the self-supporting metal phosphide/carbon nanotube multi-stage composite electrodes (NiCoP-CNT@NiCo/CP and NiFeP-CNT@NiCo/CP) were successfully constructed. In the above composite electrodes, the CNTs and internal NiCo nanowire arrays guarantee the outstanding electronic conductivity and good mechanical stability of electrodes, and the metal phosphide nanoparticles anchored on the defect sites provide abundant active sites.

The as-prepared composite electrodes NiCoP-CNT@NiCo/CP (for hydrogen evolution reaction) and NiFeP-CNT@NiCo/CP (for oxygen evolution reaction) exhibit excellent catalytic performance in alkaline solutions. Combined with our previous work (Journal of Catalysis, 2020, 391, 1-10), it was further confirmed that metal phosphides would be transformed into metal hydroxides/oxyhydroxides during the hydrogen evolution/oxygen evolution reaction process. This work provides an effective strategy for preparing a unique three-dimensional conductive network to enrich the active site and increase its electrical conductivity, which is of great significance for the design of high-efficiency electrochemical water splitting catalysts.

Zuohui Wang, a postgraduate student in the Key Laboratory of Special Functional Materials, is the first author of the paper. This work was strongly supported by the Organization Department of the Central Committee of the Communist Party of China, the National Natural Science Foundation of China, the Henan Provincial Department of Science and Technology, the Henan Provincial Department of Education, and Henan University.

Paper links: https://pubs.rsc.org/en/content/articlepdf/2020/ta/d0ta10964a