Electrolysis of CO ₂ in molten salts promises efficient carbon capture, but the underlying reaction mechanisms remain incompletely understood, as research thus far has been limited by a lack of tools for operando investigations. Here, we use a high-temperature operando Raman spectroelectrochemical system to look for signatures of reaction intermediates and study the evolution of carbon structures over electrolysis time. The analysis reveals the existence of O ₂ ²⁻ concurrently with the deposition of carbon on Au, W, Inconel, and Ni electrode materials, pointing to a common reaction mechanism with O ₂ ²⁻ as an intermediate. Secondly, the G peak of the as-deposited carbon experiences a noticeable blue-shift as the material is cooled down and purified, suggesting either a growth in crystallite size even after the electrolysis is stopped or lithium deintercalation. Elucidating the cathodic carbon deposition mechanism could help create greater value-added products and increase the economic viability of carbon capture.

The extraction of valuable carbon‐based products from CO ₂ reduction represents a promising route to reduce greenhouse gas emissions, promote circular economy practices, and facilitate the integration of energy storage sources such as Li‐ion batteries (LIBs). Using such extremely valuable sustainable products obtained from the CO ₂ capture process can solve not only the global warming problems but also the high demand of the battery industry to provide graphite and highly conductive additives. Herein, a carbon nanomaterial (CNM) extracted from CO ₂ reduction treatment is used as the conductive additive in LIB graphite anode and lithium iron phosphate cathode. The electrodes are produced by casting, using both the conventional poly(vinylidene fluoride) binder, dissolved in N‐methyl‐2‐pyrrolidone, and sodium alginate as a green, water‐soluble, alternative binder. The electrochemical performance of the CNM‐based electrodes is here compared to that of LIB cathodes and anodes produced with a commercial carbon additive. The electrodes featuring CNM offer electrochemical performance close to those of conventional electrodes in which commercial conductive additives are utilized.

Finding viable alternative catalysts for the oxygen reduction reaction (ORR) is a key issue in modern electrocatalysis. Traditional Pt/C catalysts are not viable in the long term and thus much effort has been focused on non-precious metal catalysts (NPMCs). Metal-nitrogen doped carbon materials (MNCs) have emerged as the main candidate for replacing the platinum-based catalysts. Among these materials, carbide-derived carbon (CDC), which is a type of carbon materials produced by removing the metal atoms from a carbide lattice, stand out as exceptional candidates due to easily variable porosity. The specific surface areas of CDC materials can reach around 1000-2000 m² g⁻¹ and the textural characteristics can be tuned by selection of carbides and synthesis conditions, with reproducible large-scale syntheses already shown.¹ In this work, we propose a method to introduce nitrogen and metals into a carbide derived carbon material with little loss of porosity using dicyandiamide (DCDA) and either cobalt or iron salts (Figure 1b). The CDC is derived from titanium carbide and then doped by pyrolyzing a mixture of the CDC, DCDA and either CoCl₂ or FeCl₃. The textural properties of the catalysts are probed with N₂ physisorption, the morphology with scanning electron microscopy, the surface elemental composition with X-ray photoelectron spectroscopy (XPS) and the structure with Raman spectroscopy. The catalysts‘ activity towards ORR along with the stability during 1000 cycles and methanol tolerance in 0.1 M KOH is assessed using the rotating disk electrode (RDE) method and compared to that of commercial Pt/C catalysts (Figure 1a). The catalysts are also utilized in a alkaline direct methanol fuel cell (ADMFC)² and an H₂/O₂ anion exchange membrane fuel cell (AEMFC). The catalysts are shown to retain their microporous structure after the pyrolysis with successful doping of up to 5.3 at.% of nitrogen into the surface layer of the materials as determined by XPS. The catalysts show excellent activity in 0.1 M KOH rivaling that of commercial platinum-based catalysts and are very stable during 1000 potential cycles, with the iron-based catalysts somewhat more active. Up to 3 M methanol concentration also has very minimal effect on the activity of the catalysts. In an ADMFC using the Fuma-Tech FAA3 membrane the MNC catalysts show better performance than Pt/C (Figure 1c) and in an AEMFC with the Tokuyama A201 membrane as the polymer electrolyte they also rival the Pt/C catalyst. Overall, we show that transition metal and nitrogen-doped CDCs present a viable alternative to commercial Pt/C catalysts for oxygen reduction in alkaline conditions and alkaline membrane fuel cells. References 1. S. Ratso, I. Kruusenberg, M. Käärik, M. Kook, R. Saar, M. Pärs, J. Leis and K. Tammeveski, Carbon, 113, 159–169 (2017). 2. S. Ratso, I. Kruusenberg, M. Käärik, M. Kook, R. Saar, P. Kanninen, T. Kallio, J. Leis and K. Tammeveski, Appl. Catal. B Environ., 219, 276–286 (2017). Figure 1. Comparison of ORR polarization curves in O₂-saturated 0.1 M KOH (a), pore size distributions (b) and ADMFC power densities (c) for the transition metal doped materials and commercial Pt/C. Figure 1