Boosting Hydrogen Evolution in Neutral Medium by Accelerating Water Dissociation with Ru Clusters Loaded on Mo₂CTx MXene

Abstract

Electrocatalytic hydrogen evolution reaction (HER) in mild neutral medium is a compelling goal for environmentally sustainable energy conversion, but its development is greatly limited by slow kinetics. Platinum group noble metals exhibit ultra‐high HER activities, but their scarcity and performance instability restrict wide application. Herein, taking advantage of excellent catalyst carrier properties of 2D‐layered transition metal carbides (MXenes), highly dispersed of Ru clusters anchored on Mo2CTx MXene are demonstrated as a superior HER electrocatalyst, which is prepared by a facile in situ reduction strategy. The as‐prepared Ru/Mo2CTx catalyst exhibits a very low overpotential of 73 mV to achieve a current density of −10 mA cm−2 and Tafel slope of 57 mV dec−1 in neutral medium, surpassing performance of most previously reported MXene‐based catalysts. In addition, Ru/Mo2CTx catalyst also presents superior stability compared to commercial Pt/C. Experimental results and theoretical calculations indicate that the interaction between Ru clusters modulates the electronic structure of active sites and promotes H2O dissociation and hydrogen desorption.

Weakening Mo–H Bond of Mo2C MXene Cocatalyst by Increased Antibonding-Orbital Occupancy State for Superior Photocatalytic Hydrogen Production

“…The lattice fringe of 0.335 nm corresponds to CdS nanoparticles (Figure A 1 ), while 2H phase layered MoS 2 with a hexagonal lattice spacing of 0.62 nm ,, (Figure A 2 ) can be inset on the layered Mo 2 CT x surface, which presents a smooth layered structure of MoS 2 –Mo 2 CT x in Figure S2D. Importantly, the Mo 2 CT x with the lattice fringe size of 0.27 nm (Figure A 3 ) as the substrate shows the uniform single-crystal arrangement of diffraction patterns in the select area electron diffraction (SAED) image (Figure A 4 ). In addition, as exhibited in the element mapping images (Figure B–B5), the Mo and C elements uniformly distribute on the thin-layered Mo 2 CT x while the Cd and S elements accumulate on the Mo 2 CT x surface to form the MoS 2 –Mo 2 CT x /CdS.…”

“…If the occupancy state of the antibonding orbital for Mo is effectively increased via charging a large number of antibonding electrons ( E a ), which is essential to optimize the adsorption energy of H ads between the active Mo centers and H ads species, it is reasonable to believe that the strong Mo–H ads bonds of Mo 2 CT x with the high density of empty d-orbitals can be successfully weakened. Regrettably, the current research studies only focus on the electron density modulation of active sites to regulate hydrogen adsorption energy through loading metals, , doping, , and constructing heterostructure. − To the best of our knowledge, few concentrations have focused on such imperative research on the direct regulation of Mo–H ads bond strength in Mo 2 CT x by the occupancy state of the antibonding orbital for Mo sites to optimize atomic H adsorption and desorption. In view of the close relation between hydrogen binding energy and occupancy state of Mo 4d antibonding orbitals, it is definitely expected to optimize the Mo–H ads bonds in Mo 2 CT x by increasing the occupancy state of Mo 4d antibonding orbitals.…”

“…If the occupancy state of the antibonding orbital for Mo is effectively increased via charging a large number of antibonding electrons (E a ), which is essential to optimize the adsorption energy of H ads between the active Mo centers and H ads species, it is reasonable to believe that the strong Mo−H ads bonds of Mo 2 CT x with the high density of empty d-orbitals can be successfully weakened. Regrettably, the current research studies only focus on the electron density modulation of active sites to regulate hydrogen adsorption energy through loading metals, 29,30 doping, 31,32 and constructing heterostructure. 33−35 To the 36 To be specific, the Mo 2 CT x aqueous solution was added to hydrochloric acid (40 mL) containing ammonium fluoride (2 g) under stirring for 1 h and then transferred into a Teflon-lined vessel at 140 °C for 24 h. The obtained product was washed with pure water until the pH value reached 6.0 and dried in vacuum at 60 °C for 24 h, and was referred to as Mo 2 CT x .…”

Single atom supported on MXenes for the alkaline hydrogen evolution reaction: species, coordination environment, and action mechanism

“…13,14 Fortunately, many studies have shown that Mo-based MXenes have great potential for application in the HER field. [15][16][17][18] Such as, the research of Zhi et al showed that Mo-based MXenes effectively avoided the toxic effect of the F-terminal group on the HER due to the weak Mo-F bond, so they had lower overpotential than Ti-based MXenes and showed better HER performance. 19 In particular, Mo-based MXenes exhibit high electrocatalytic activity and stability over a wide pH range, meeting the basic requirements of catalysts for alkaline hydrogen precipitation reactions.…”

Anchoring 0D Cd0.5Zn0.5S nanoparticles on a 3D porous N-doped Ti3C2Tx MXene matrix for efficient photocatalytic hydrogen evolution

“…MXenes, a class of 2D layered materials made up of transition metal carbides and/or nitrides with an analogous graphene structure, 11,12 represented by the general formula M n+1 X n T x (where M is a transition metal, X is either C or N, n can be 1, 2, or 3, and T x refers to the surface functional groups), 13,14 have shown competitiveness in energy conversion applications due to the fascinating surface functionalization effects and edgeexposed active sites. 15 Specifically, MXene has been widely exploited as a cocatalyst for photocatalytic H 2 evolution due to its exceptional conductivity, adjustable stratified structures, functionalized surface terminal groups, and abundant active vacancy defects.…”