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

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 degrees C, the formed Pt-SnTiOx coatings are compact and stable on the Ti substrates due to the strong TiOx-Ti bonding, while the enhanced electron transfer from SnOx to metallic Pt led to high-exposure active sites, and hence, the Pt-SnTiOx coating presents an enhanced HOR activity and prolonged service life compared with the Pt-TiOx and Pt-SnOx 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. A new-concept Ti-based gas diffusion electrode is successfully developed for hydrogen-related metal electrowinning with low power consumption, high current efficiency, and long service life.