In Situ Electrosynthesis of MAX‐Derived Electrocatalysts for Superior Hydrogen Evolution Reaction

Abstract

more mature precious metal catalysts such as Pt. However, the high cost, limited earth reserves, and easy aggregation property promote the optimization of precious metal usage and the development of non-precious metal catalysts. [4] Therefore, the coupling mechanism of the conductive matrix and the Pt nanoparticles can greatly stabilize the catalytic activity and reduce the production cost at the same time. [5] 2D transition metal carbides and nitrides (MXenes) of high electrical conductivity, hydrophilicity, large specific surface area, and adjustable surface characteristics have shown great potential in the field of electrocatalysis. [6] MXenes specifically refer to a type of material with M n + 1 X n T x element composition (M, transition metal element, X, C, or N atom, and T, surface functional group, and n = 1-4, atomic layer number). [7] Recently, Cui et al. proposed a method to take advantage of the hydrophilicity and reducibility of MXenes to immobilize highly active nano/atomic metal Pt on Ti 3 C 2 T x MXene sheets, while adding single-walled carbon nanotubes as a binder. The prepared hierarchical HER catalyst (in the form of a membrane) showed high stability during 800 h operation. [8] And a strategy for electrochemical in situ synthesis of Mo 2 TiC 2 T x MXenes supported single platinum atoms was proposed. The vacancy introduced by electrochemical exfoliation of MXenes became the active site anchored by Pt, enhancing the activity of HER. [9] Besides, low Pt dose supported on multilevel hollow MXenes catalyst, Pt 3 Ti nanoparticles formed in situ based on Ti from the surface of Ti 3 C 2 T x , and PtNi ultrathin nanowires with MXenes provided an actual MXenes coupling concept with Pt, enabling the development of high performance and stability of HER catalysts. [4,10,11] According to current literature reports, various surface groups and intrinsic defects of MXene have remarkable effects on the anchoring and dispersion of Pt atoms/cluster. [12] At present, the most extensive preparation method is to etch the A layer atoms in the MAX phase (A represents the elements of 13 or 14 groups in periodic table) by HF or LiF + HCl. Theoretical predictions have confirmed some pure MXenes are promising HER catalysts based on the premise that surface functional groups are O or OH groups. [13] Nevertheless, the experimental results showed poor catalytic activity of pure MXenes, generally due to the wet chemical etching of the precursor MAX phase to prepare MXenes, which introduced MAX phases are frequently dominated as precursors for the preparation of the star material MXene, but less eye-dazzling by their own potential applications. In this work, the electrocatalytic hydrogen evolution reaction (HER) activity of MAX phase is investigated. The MAX-derived electrocatalysts are prepared by a two-step in situ electrosynthesis process, an electrochemical etching step followed by an electrochemical deposition step. First, a Mo 2 TiAlC 2 MAX phase is electrochemically etched in 0.5 m H 2 SO 4 electrolyte. Just several hours...

One-Step Electrochemical Synthesis and Surface Reconstruction of NiCoP as an Electrocatalyst for Bifunctional Water Splitting

“…Transition-metal-based electrocatalysts have shown great potential for overall water splitting over the past few years. Various oxides (MoO x ) [ 9 ], hydroxides (Ni(OH) 2 ) [ 10 , 11 ], sulfides (MoS 2 ) [ 12 ], selenides (MoSe 2 ) [ 13 ], nitrides (VN) [ 14 ], and carbides (MXene) [ 15 , 16 ] materials have been extensively reported as water splitting electrocatalysts. Among the aforementioned catalysts, transition metal phosphides (TMPs) possess a hydrogenase-like structure, and are regarded as promising nonprecious electrocatalysts for overall water splitting [ 17 , 18 , 19 , 20 , 21 , 22 ].…”

Structural Engineering Enabled Bimetallic (Ti1‐yNby)2AlC Solid Solution Structure for Efficient Electromagnetic Wave Absorption in Gigahertz

“…For the C1s spectrum, the peak at 281.5 eV of Ti 2 AlC matches with Ti–C, which is shifted to a positive binding energy value (281.7 eV) in Ti 1.2 Nb 0.8 AlC due to the influence of Nb–C bond. [ 46 ] The other peaks about 284.8, 285.8, and 289 eV have contributions from the bonds of C–C, C—O, and C=O, respectively. As a result, the foreign atoms with different electronegativity compared to host atoms will change the distribution of the electron cloud and lead to the formation of electric dipoles on the EM field, contributing to EM wave dissipation.…”

MXene‐based Materials for Water Splitting: Synthesis and Modification

“…The prepared MoS 2 ‐Ti 3 C 2 MXene electrocatalyst possessed abundant active sites, excellent conductivity and structural stability. The activity of the MAX phase was investigated [97] . Max‐derived electrocatalysts were prepared using a two‐step in situ electrosynthesis process, namely electrochemical etching and deposition.…”

“…The activity of the MAX phase was investigated. [97] Max-derived electrocatalysts were prepared using a two-step in situ electrosynthesis process, namely electrochemical etching and deposition. The first step is the electrochemical etching of the Mo 2 TiAlC 2 MAX phase in a 0.5 M H 2 SO 4 electrolyte.…”