Deciphering the dynamic structural evolution of oxygen vacancies enriched SrFe12O19 for efficient reverse water gas shift reaction

[Display omitted] •A series of oxygen vacancy enriched SrFe12O19 and transition metal doped MxSrFe12-xO19 (where M = Zn2+, Cu2+, Ni2+ or Co2+ and x = 0.4) catalysts is prepared for rWGS reaction.•The doping caused oxygen vacancy enrichment and enhanced reducibility in the SrFe12O19 system.•The Cu-doped SrFe12O19 exhibits 100 % CO selectivity with a CO production rate of 2850 mmol h−1 gcat-1 at 500 °C and displays exceptional stability tested for 200 h without showing signs of deactivation.•The characterization of catalysts following activity test demonstrates the formation of several iron species (Fe3O4, Fe3C, and Fe5C2).•The relative amount of these iron species issignificantly influenced by doping elements, thereby affecting CO selectivity. The Reverse Water-Gas Shift (rWGS) reaction is recognized as a potentially promising pathway to serve the dual purpose, possible shifting of CO2 from a linear economy to a circular and positive economic impact in the current industrial process. This study is engaged to develop a series of oxygen vacancies enriched M−type strontium hexaferrite (SrFe12O19) catalysts via doping of transition metals like Cu, Zn, Co, and Ni for the rWGS reaction. Cu-doped SrFe12O19 exhibited 100 % CO selectivity and a CO production rate of 2850 mmol h−1 gcat-1, at a comparatively lower temperature (500 °C), outpacing the performance of almost all non-precious metal-based catalytic systems. Moreover, the catalyst was active without the requirement of the H2 pre-reduction procedure and displayed remarkable stability tested up to 200 h without any significant deactivation, making it more industrially relevant. The characterization of as-prepared catalysts indicates the enrichment of oxygen vacancies and reducibility after the involvement of the dopant in the SrFe12O19 system. The formation of various iron species (Fe3O4, Fe3C, and Fe5C2) was revealed by the in-situ studies and post-reaction characterizations of the catalyst system, and their relative amounts were significantly affected by the nature of doping elements, which subsequently influenced the CO selectivity. The dynamic structural evolution and surface-adsorbedspecies were identified usingin-situ Raman and DRIFTS studies. Finally, the structure–activity relationship was rationalized through not only several ex-situ/in-situ characterization techniques but also an in-detailed Density functional theory (DFT) study.