Precision N-species engineering in Pt–N4via ring reconstruction towards efficient alkaline water electrolysis†
Abstract
Pyridinic-N (N[6]) and pyrrolic-N (N[5]) are vital for the performance of metal–nitrogen–carbon (M–N–C) catalysts, yet precise control over them remains elusive. Here, we theoretically explore the impact of N[5]/N[6] atomic ratios on the stabilities and activities of Pt–N4–C, a leading hydrogen evolution catalyst. Guided by insight, we successfully synthesize the Pt–N4–C with an optimized 1 : 1 N[5]/N[6] ratio via hydrogen-assisted pyrolysis of ZIF-8@ZIF-67, followed by Pt coordination. In situ generated Co nanoparticles convert partial N[6] to N[5], inducing a ring reconstruction and fine-tuning of N ratios. The internal N-engineering of Pt1 coordinated with N[5]/[6]C and external OH adsorption on Con significantly reduce the alkaline water splitting energy barrier, achieving an exceptionally low voltage (1.82 V) and excellent stability (400 h@1 A cm−2) in membrane electrode assemblies. This work offers crucial insights into optimizing N[5]/N[6] ratios to enhance the performance of M–N–C catalysts.