Cation Vacancy Clusters in Ti₃C₂T_x MXene Induce Ultra‐Strong Interaction with Noble Metal Clusters for Efficient Electrocatalytic Hydrogen Evolution

Abstract

MXenes are promising substrates for supported noble metal electrocatalysts. Yet, it is a significant challenge to modulate the metal-support interaction (MSI) for enhancing catalytic performance. Herein, employing a facile HF etching method, the cation vacancy structures in Ti 3 C 2 T x MXenes are controllably tuned, producing nearly vacancy-free (Ti 3 C 2 T x -V 0 ), single Ti atom vacancy (Ti 3 C 2 T x -V S ), or Ti vacancy cluster (Ti 3 C 2 T x -V C ) engineered MXenes. Ruthenium atomic clusters, as a model catalyst, successfully anchor on all MXene substrates. Different from the terminal -O/-F coordination groups on routine Ti 3 C 2 T x MXene surfaces, the Ti vacancy clusters in Ti 3 C 2 T x -V C create unique lattice carbon ligand environment toward Ru species, which induces ultra-strong MSI. As a result, compared to Ti 3 C 2 T x -V 0 and Ti 3 C 2 T x -V S , the Ti 3 C 2 T x -V C modulated Ru clusters (Ru@Ti 3 C 2 T x -V C ) exhibit the optimized balance of H 2 O adsorption/dissociation and OH/H desorption, thereby delivering superior electrocatalytic performance in the alkaline hydrogen evolution reaction (HER). Within the wide range from laboratory-level (90 mA cm −2 ) to industrial-level (1.5 A cm −2 ) current density, Ru@Ti 3 C 2 T x -V C outperforms commercial Pt/C in terms of overpotential and mass activity. Moreover, as a universal substrate for noble metal catalysts, Ti 3 C 2 T x -V C can also anchor Ir/Pt/Rh atomic clusters and enable excellent HER catalytic activity. This work expands the scope of the MSI between MXene and noble metal catalysts.

Accelerating the Phase Formation Kinetics of Alluaudite Sodium Iron Sulfate Cathodes via Ultrafast Thermal Shock

“…The consumption of traditional fossil fuels inevitably results in an energy crisis and environmental contamination, requiring robust development of clean and renewable energy sources. − In recent years, electrochemical energy storage has become a crucial tool for establishing new energy systems and facilitating energy transformation. − Sodium-ion batteries (SIBs) exhibit similar energy storage mechanisms and enhanced safety compared to lithium-ion batteries. − Moreover, the costs of energy storage power stations will be substantially diminished owing to the exceedingly widespread sodium source on Earth. − However, developing cathode materials that possess comprehensive electrochemical performance poses a significant challenge in SIBs. − …”

Immobilizing Ultralow Loading Platinum Nanoparticles onto MXene through Defect Engineering to Enhance the Activity of the Hydrogen Evolution Reaction

“…On the other hand, adopting an appropriate conductive matrix to compound with Pt NPs can effectively boost the catalytic activity by modulating the d-band structure, owing to electron transfer at the heterointerfaces. − Because of their vast surface areas for increasing dispersity as well as avoiding aggregation of Pt NPs, two-dimensional (2D) materials are considered to be ideal substrates for supporting Pt NPs. − MXenes have a formula of M n +1 X n T x ( n = 1, 2, 3), in which M represents an early transition metal, X stands for carbon and/or nitrogen, and T x is surface functional groups, such as −O, −OH, or −F . They receive increasing attention in a variety of 2D materials due to their highly hydrophilic surface, rich chemistries, and metallic conductivity. − These benefits are hardly attainable in conventional 2D materials such as graphene, double metal hydroxides (LDH), C 3 N 4 , and so on. , Nonetheless, metallic NPs are prone to be located onto low-coordinated regions of MXenes, such as the edges, resulting in uneven distribution. − It has been proposed to build defect-enriched 2D materials for immobilizing metallic NPs, which can further enhance the activity and stability of the NPs. − However, creating defects in MXene is commonly realized by raising the concentration of hydrofluoric acid during the synthetic process, which would damage the MXene crystal. − It is worth noting that MXenes tend to form oxidation layers on their surfaces owing to the reaction with oxygen molecules in air or dissolved in water. − Metal oxides can generally undergo anion and cation exchange with aprotic solvents (e.g., N -methyl­pyrrolidone, NMP) so that metal cations and oxygen anions partially dissolve out by coordinating with ligand molecules, eventually creating metal and oxygen vacancies …”

Flexible MXene/Nanocellulose Composite Aerogel Film with Cellular Structure for Electromagnetic Interference Shielding and Photothermal Conversion

“…MXene, an emerging class of two-dimensional transition metal carbides and/or nitrides produced by etching the “A” layer from the precursor MAX phase, was developed by Gogosti and his co-workers in 2011. , Thanks to their remarkable characteristics such as their large specific surface, hydrophilicity, and metal-like conductivity, MXene is extensively studied in the fields of energy harvesting, storage and conversation, environment, biological medicine, catalyst, etc. − With advances in research, MXene has been confirmed as one of the potential candidates for EMI shielding in 2016. , However, the mechanical strength of macroscopic materials prepared with pure MXene is not satisfactory, leading to difficulties in practical application. , Fortunately, MXene nanosheets have a large number of surface groups (such as −OH, −F, etc. ), which contribute to facilitating their interaction with other components to increase the mechanical strength of macroscopic materials. , …”