Modulation of Surface Ti–O Species in 2D-Ti₃C₂T_X MXene for Developing a Highly Efficient Electrocatalyst for Hydrogen Evolution and Methanol Oxidation Reactions

Abstract

Developing cost-effective and earth-abundant noblemetal-free electrocatalysts is imperative for the imminent electrochemical society. Two-dimensional Ti 3 C 2 T X (MXene) exhibits tunable properties with high electrical conductivity and a large specific surface area, which improve its electrochemical performance. Herein, the lowtemperature annealing method is used to enrich MXene with a maximum number of Ti−O terminals without formation of titanium dioxide (TiO 2 ) under neutral pH conditions. MXene annealed at 200 °C is found to have a large number of Ti−O termination groups, resulting in a large electrochemically active surface area and increased active sites (−O termination groups) and hence excellent electrocatalytic performance compared to other samples as well as previous reported work. The optimized sample is found to show the lowest overpotential value of 0.07 V at 10 mA cm −2 and a Tafel slope of 0.15 V dec −1 toward the hydrogen evolution reaction (HER), whereas for the methanol oxidation reaction (MOR), the current density is 18.08 mA cm −2 , and the onset potential is −0.51 V. In addition, it also shows long-term stability and durability toward HER as well as MOR.

Preparation and Study of Ti3C2Tx MXene–Deficient In Situ Anchored Fe−Co Alloy Nanoparticle Electrocatalyst for Hydrolysis and Hydrogenolysis

“…Figure 5(d) shows the Ti 2p spectrum of Fe−Co/Ti 3 C 2 T X obtained after loading Fe and Co. In this spectrum, the Ti 3+ and Ti 2+ peaks are weaker compared to those ofTi 3 C 2 T X , [24–25] which is because the Fe−Co alloy disrupts the C−Ti−O and C−Ti−OH coordination environments of the original Ti 3 C 2 T X .Thisresults in an upward shift of the binding energy. The O 1s spectrum of Ti 3 C 2 T X shows peaks at 531.88 eV, 529.38 eV, and 459.18 eV that respectively correspond to the Ti−O, C−Ti−Ox, and C−Ti−(OH) x coordination states, [26] as shown in Figure 5(b).…”

Radiation-Induced Surface Modification of MXene with Ionic Liquid to Improve Electrochemical Properties and Chemical Stability

“…MXene, an emerging family of 2D-layered materials, has attracted extensive attention over the past few years, which can be represented as M n +1 X n T x (where M = Ti, Nb, Mo, V, etc. ; X = C and N; Tx is terminating groups such as –O, –F, and –OH species; and n = 1, 2, 3, or 4). – They can be typically obtained by selectively etching A layers (where A represents an element of IIIA or IVA) from the MAX phase, forming a multiple-layer structure attached with different surface functionalities. , MXenes have shown great potential in the fields of energy storage devices, water desalination, catalysis, electromagnetic interference shielding, etc., due to their excellent electrical conductivity, good hydrophilicity, large specific surface areas, and high thermal stability. ,– Among different kinds of MXenes, Ti 3 C 2 T x has been widely studied for supercapacitor electrodes owing to its excellent structural stability and ultrahigh metallic conductivities (9800 S cm –1 ) …”

Surface Modification Effect on V-Doped Ti3C2Tx as Bifunctional Catalyst Electrodes for Symmetric Supercapacitor and the Hydrogen Evolution Reaction

“…Hydrogen production through electrochemical water splitting is considered a state-of-the-art, sustainable energy method. , The electrocatalytic cell undergoes two main reactions to produce hydrogen (H 2 ) and oxygen (O 2 ) for the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode, respectively. , As a result, several research teams are working on modifying the surface terminal groups of Ti 3 C 2 T x to increase its catalytic activity and enable its use as a bifunctional catalyst for overall water-splitting applications (for both HER and OER activities). , Vanadium-doped Ti 3 C 2 T x is believed to be an effective catalyst for electrochemical water splitting as a result of its strong hydrogen-binding strength (high Gibbs free energy). The potential of oxygen as an energy source has been recognized, but its high cost and limited availability have hindered its commercialization and use in industrial applications. − …”