Simultaneous Sulfite Electrolysis and Hydrogen Production Using Ni Foam-Based Three-Dimensional Electrodes

Abstract

The electrochemical oxidation of sulfite ions offers encouraging advantages for large-scale hydrogen production, while sulfur dioxide emissions can be effectively used to obtain value-added byproducts. Herein, the performance and stability during sulfite electrolysis under alkaline conditions are evaluated. Nickel foam (NF) substrates were functionalized as the anode and cathode through electrochemical deposition of palladium and chemical oxidation to carry out the sulfite electro-oxidation and hydrogen evolution reactions, respectively. A combined analytical approach in which a robust electrochemical flow cell was coupled to different in situ and ex situ measurements was successfully implemented to monitor the activity and stability during electrolysis. Overall, satisfactory sulfite conversion and hydrogen production efficiencies (>90%) at 10 mA·cm–2 were mainly attributed to the use of NF in three-dimensional electrodes with a large surface area and enhanced mass transfer. Furthermore, stabilization processes associated with electrochemical dissolution and sulfur crossover through the membrane induced specific changes in the chemical and physical properties of the electrodes after electrolysis. This study demonstrates that NF-based electrocatalysts can be incorporated in an efficient electrochemical flow cell system for sulfite electrolysis and hydrogen production, with potential applications at a large scale.

Electrochemical behavior of a Ni3N OER precatalyst in Fe-purified alkaline media: the impact of self-oxidation and Fe incorporation

“…According to the TXRF result, the Fe concentration of our reagent grade 1 M KOH aqueous electrolyte was ~ 1.15 mg·L -1 . To ensure the uniform uptake of Fe impurities on our sample electrodes 57,58 and evaluate their OER performances in a condition close to practice, 67 we used a flow cell system (Fig. S16), 68 about which more details are available in the ESI.…”

“…This may be the result of the improved mass transfer due to the use of a flow cell. 57,68 From the comparisons to literature values, the use of a flow cell is effective for further enhancing the geometric OER activity. This strategy can also be adapted to other foam-type electrocatalysts.…”

“…Furthermore, to check the impact of Fe impurity incorporation on measured OER activities, the Ni 3 N/Ni foam electrodes were tested for the OER in Fe-unpurified alkaline media ("unpurified 1 M KOH") as well. To more deliberately and evenly introduce trace Fe into the self-oxidized Ni 3 N/Ni foam 57,58 and evaluate the OER activity in a condition close to practical conditions, a flow cell was used. Specifically, we conducted long-term OER chronopotentiometric (CP) tests to examine the relationship between the electrochemical changes and Fe incorporation over time.…”

Electrocatalysts Based on Novel Carbon Forms for the Oxidation of Sulphite

“…Heeding the results presented in Figure 13a,b we can conclude that it is possible to build different types of effective electrochemical cells such as the fuel cells: Na 2 SO 3 /O 2 ; SO 2 /O 2 ; SO 3 /NO 3 [58] and Na 2 SO 3 /H [59] based on electrolyzers that can be used to cleanse natural and industrial pollutants while at the same time yielding a surplus of energy.…”

Concurrent Electrolysis under Pressured CO2 for Simultaneous CO2 Reduction and Hazardous SO2 Removal

“…Then, sulfite is commonly oxidized using strong oxidants (ozone and H 2 O 2 , etc.) for S­(IV) species removal . The electrochemical step serves as an alternative strategy for sulfite oxidation reaction (SOR) to prevent the use of expensive oxidants.…”