The reduction mechanism of C1 product from carbon dioxide catalyzed by Ni-doped g-C3N4

This work employs density functional theory (DFT) to scrutinize the catalytic efficacy of nano nickel (Ni) clusters supported by graphitic carbon nitride (Nin@g-C3N4, where n ranges from 1 to 6) in the context of the CO2 reduction reaction (CO2RR). Structural examination revealed that Nin@g-C3N4 possesses a substantial binding energy (-1.63 eV to -7.72 eV), confirming the structural stability of the catalyst in the CO2RR. Electronic structure analysis revealed a pronounced orbital overlap near the Fermi level between the 3d orbital of Ni atoms and the 2p orbital of adjacent cavity nitrogen atoms in Nin@g-C3N4. Further insights are gleaned from the calculations of the Bader charge and energy band, indicating significant charge transfer and band gap alteration, suggesting enhanced conductivity due to Ni doping on g-C3N4. The catalytic performance in the CO2RR is predominantly influenced by the size of the doped Ni clusters. The Ni4@g-C3N4 cluster demonstrated optimal efficiency in producing formic acid (HCOOH) with a limiting potential of -0.12 V. In contrast, the Ni5@g-C3N4 cluster excels in methane (CH4) formation, with a limiting potential of -0.35 V. Additionally, these catalysts exhibit marked inhibition of the hydrogen evolution reaction, further underscoring their potential in CO2RR applications.