CO2 Hydrogenation Using Size-dependent Ru Particles Supported on g-C3N4

Efficient catalysis of CO₂ hydrogenation holds significant promise for addressing environmental concerns and advancing sustainable energy solutions. In this study, we report the synthesis of a novel series of Ru-supported on graphitic carbon nitride (g-C₃N₄) catalysts, with a focus on the impact of ruthenium (Ru) loading on the thermocatalytic performance. Varying Ru concentrations were introduced, including 0.2, 0.5, 1.0, 2.0, and 5.0 wt%, resulting in different Ru particle sizes on g-C₃N₄ support. Through a multifaceted characterization approach, it was observed that the catalyst containing 1 wt% Ru loading displayed superior performance, with a high density of active sites, indicated by an enhanced CO₂ conversion rate of 36.8 % at 450 °C and a CO yield of 25 %. This catalyst also exhibited remarkable CO selectivity of 83 % at 375 °C. Conversely, lower loadings of 0.2 and 0.5 wt % Ru were found to be less effective, yielding minimal CO₂ conversion. Loadings above 1 wt% Ru, while achieving high CO₂ conversion, demonstrated a preference for CH₄ production over CO, indicating lower selectivity for the desired product. This study elucidates the critical role of Ru nanocluster size in the catalytic activity and selectivity, with 1 wt % Ru-supported g-C₃N₄ emerging as a promising candidate for selective CO generation from CO₂ hydrogenation, offering a pathway for the valorization of CO₂ as a raw material in the chemical industry.