Electron modulation by atomic Ir site decoration in porous Co/N co-doped carbon for electrocatalytic hydrogen evolution

The rational design of materials at atomic scale as efficient and stable electrocatalysts for hydrogen evolution reaction (HER) is critical for energy conversion. Herein, we report a novel hybrid nanostructure with iridium (Ir) and cobalt (Co) atomic pair configuration anchored in porous nitrogen-doped carbon (pNC) nanosheets (denoted as IrCo-pNC) for electrocatalytic HER. Experimental investigations and theoretical calculations reveal that the interaction between Ir and Co species in pNC promotes electron accumulation and depletion around isolated Ir and Co atoms, respectively, resulting in a local asymmetry electron density distribution. Density functional theory calculations also suggest that the electrons transfer from Co to adjacent Ir atom causing the down shift of the d-band center of Ir 5d in IrCo-pNC catalyst, thus optimizing the adsorption of hydrogen on Ir sites. The as-prepared IrCo-pNC exhibits significant HER performance with an overpotential of 21 mV to achieve a current density of 10 mA·cm⁻² in 0.5 M H₂SO₄. This work provides insight into the role of asymmetry electron density distribution in nanomaterials in regulating HER electrocatalysis.