Structural transformation of carbon-encapsulated core-shell CoNi nanoparticles during magnetically induced CO2 reduction into CO

Abstract

Controlling product distribution in CO 2 hydrogenation is of great scientific interest, the selective CO production through the reverse water-gas shift reaction (RWGS) being one of the most investigated processes. Herein, we report the synthesis of new core-shell Co@Ni NPs encapsulated in carbon ( Co@Ni@C ) to prevent their aggregation at the high-temperatures reached during magnetically induced catalysis. This bifunctional system has been simultaneously used as heating agent and catalyst for the magnetically induced hydrogenation of CO 2 . While at low magnetic fields Co@Ni@C produces CH 4 :CO mixtures, at higher field amplitudes it selectively generates carbon monoxide. Indeed, Co@Ni@C has shown to be one of the most active catalysts reported to date, which reaches a maximum conversion of 74.2% with complete selectivity towards CO at 53 mT and 300 kHz. In addition, recycling and cyclability experiments have demonstrated that Co@Ni@C becomes fully selective for CO after being exposed to high field amplitudes ( i.e. reaction temperature above 500 °C), even when it exposed to low magnetic fields again. This change in the selectivity is due to an atomic rearrangement of the core-shell structure, as was confirmed by EDX, XAS, TPR and TPD analysis. • Core-shell Co@Ni NPs encapsulated in carbon ( Co@Ni@C) have been used as catalyst for magnetically induced CO 2 hydrogenation • While at low magnetic fields Co@Ni@C produces CH 4 :CO mixtures, at higher fields it selectively generates CO • Co@Ni@C reaches a maximum conversion of 74.2% with complete selectivity towards CO at 53 mT • Co@Ni@C becomes fully selective to CO after the first catalytic cycle due to an atomic rearrangement of the core-shell structure

Topics & Concepts