Nanoconfinement Engineering Enables Pt Nanocrystals in MOF-on-MOF Derived Nanoporous Carbon Microspheres for Hydrogen Evolution

Abstract

Developing Pt-based catalysts with maximized atomic utilization and optimized electronic structures remains crucial for accelerating the cathodic hydrogen evolution reaction (HER). Herein, we develop a MOF-on-MOF-derived confinement strategy to construct a defect-mediated nanoconfined Pt microenvironment within hierarchically nanoporous carbon microspheres (NCMS), yielding the final catalyst denoted as Pt@NCMS. Specifically, the pre-fabricated Zn/Cu-BTC precursor undergoes pyrolysis and selective etching to generate an interconnected porous carbon enriched with defect sites, enabling confinement of platinum nanocrystals with enhanced metal-support electronic coupling. Structural characterizations reveal that the nanoconfined architecture effectively suppresses Pt aggregation, enhances carbonaceous graphitization, and exposes abundant active sites. XPS and X-ray absorption spectroscopy demonstrate interfacial charge redistribution between Pt species and the defect-rich carbon matrix, which indicates modulation of the Pt electronic structure. Density functional theory calculations further confirm that the nanoconfined Pt microenvironment shifts the Pt d-band center to a lower energy level, thereby optimizing hydrogen adsorption and reducing the rate-determining energy barrier for HER. Benefiting from hierarchical porosity, nanoscale confinement, and electronic modulation, Pt@NCMS exhibits outstanding HER activity with low overpotentials of 19.0 mV in 0.5 M H2SO4 and 51.0 mV in 1.0 M KOH at 10 mA cm–2, together with excellent long-term stability over 100 h. This work demonstrates a feasible strategy for engineering nanoconfined Pt electronic microenvironments for high-performance electrocatalysis.