Preparation of a nanoporous active tungsten foil by two-step anodizing and deoxidized annealing for hydrogen evolution reaction

Abstract

Nanoporous metals made by anodizing represent a class of active materials with unique structural properties. In this work, nanoporous active W foils (NPAWFs) are prepared via two-step anodizing and deoxidized annealing in hydrogen atmosphere. During the course of this research, the anodizing and annealing conditions have been optimized systematically. The morphology, composition and catalytic property of as-prepared NPAWFs have been characterized by field-emission scanning electron microscope, energy dispersive spectrometer, x-ray diffraction and electrochemical measurements. The final results show that a reduction in the anodizing voltage from 60 V for 60 min to 40 V for 60 min causes better growth of nanoporous structure, and the deoxidation at 700 °C for 3 h can remove oxygen in the nanoporous layer while retaining the nanoporous structure and activity. Compared with non-treated W foil, the NPAWF exhibits superior hydrogen evolution reaction (HER) activity with a low onset overpotential of 199 mV and Tafel slope of 84 mV dec^-1 due to its nanoporous structure and large specific surface area. Additionally, the NPAWF shows outstanding long-term stability in acidic media, indicating it is a promising transition metal HER electrocatalyst and can also be used as a high active matrix material.