Alkaline functional chromium carbide: Immobilization of ultrafine ruthenium copper nanoparticles for efficient hydrogen evolution from ammonia borane hydrolysis

Designing cost-effective and high-performance heterogeneous nanocatalysts for ammonia borane hydrolysis is of extreme significance for hydrogen energy application, yielding a great challenge. Recently, MXene, a broad family of two-dimensional layered materials consisted of transition metal carbide/nitride materials, have garnered considerable attention for energy-related applications. Herein, for the first time, we introduce a facile strategy for designing a novel alkaline MXene chromium carbide (Cr₃C₂) coordinating ruthenium-copper nanoparticles (RuCu NPs) with optimal geometric configuration by introducing diamine species. The introduction of diamine species can efficiently tune the coordinating environment of two-dimensional Cr₃C₂ (MXene) surface, resulting in a uniform distribution of RuCu NPs with the size of 1.7 nm on Cr₃C₂ surface. The resulting alkaline Cr₃C₂ coordinating RuCu nanocatalytic system exhibits remarkable catalytic kinetics of ammonia borane hydrolysis (ABH) without any additives, affording a turnover frequency (TOF) value of as high as 1102 mol_H2mol_Ru^-1min⁻¹ with 100 % hydrogen selectivity at room temperature. This enhancement is attributed to alkaline diamine species, which not only modifies the coordinating environment, but also optimizes the localized charge distribution and surface d center of active sites, achieving suitable thermodynamic energy barrier and favorable adsorption/desorption behavior for accelerating ammonia borane hydrolysis. This work provides a novel strategy for architecture of heterogeneous MXene-based nanocatalysts as Lewis system for hydrogen energy application.