Thermal reconstruction engineered titanium-based gas diffusion electrodes for robust and energy-saving hydrogen hydrometallurgy

Abstract

Hydrogen hydrometallurgy is one of the desirable alternatives to deal with the high power consumption and high CO₂ emissions caused by traditional energy strategies in industrial fields, and a highly robust hydrogen depolarization anode for the hydrogen oxidation reaction (HOR) is essential to replace the traditional oxygen evolution reaction process. In this work, we prepare new-concept gas diffusion electrodes (GDEs) derived from titanium-based materials by using the thermal reconstruction of platinum, tin and titanium precursors on titanium felt substrates (denoted as Pt–SnTi). After heat treatment at 500 °C, the formed Pt–SnTiO_x coatings are compact and stable on the Ti substrates due to the strong TiO_x–Ti bonding, while the enhanced electron transfer from SnO_x to metallic Pt led to high-exposure active sites, and hence, the Pt–SnTiO_x coating presents an enhanced HOR activity and prolonged service life compared with the Pt–TiO_x and Pt–SnO_x coatings. To evaluate the feasibility of the resulting Ti-based GDE in hydrogen hydrometallurgy techniques, we applied the Pt–SnTi GDE in copper electrowinning and zinc electrowinning. After 72 + 72 hour operation, the low cell voltage (Cu: below 0.63 V; Zn: below 1.41 V), low power consumption (Cu: below 520 kW h t⁻¹; Zn: below 1220 kW h t⁻¹) and high Faraday efficiency (Cu: above 98%; Zn: above 90%) confirm the good technical prospects for its applications in hydrogen hydrometallurgy. Moreover, high performance was also achieved in an industrial electrolyte and under long-term operating conditions for 230 hours (including 28 cycles of Zn stripping), and the high robustness endows these Ti-based GDEs with further promising applications in the field of hydrogen industries.