Insights on the Corrosion and Degradation of MXenes as Electrocatalysts for Hydrogen Evolution Reaction

Abstract

MXenes, known as the graphene-like two-dimensional transition metal carbides, carbonitrides, or nitrides, have been considered as promising electrocatalysts to replace benchmark Pt for hydrogen evolution reaction (HER). Despite the success in fabricating MXenes, their application in catalysis still faces great challenges. One critical drawback is the rapid corrosion and structural evolution of MXenes during storage and HER. In this work, the corrosion and structural evolution of various MXenes in air, aqueous colloidal solutions, and under HER conditions are reviewed. The degradation/structural mechanism of MXenes and effects of structural evolution on the HER activity are in dispute. Preliminary protocols are proposed for future MXene storage and design for HER application. This review provides valuable information to better prevent corrosion of MXenes before and after servicing as HER catalysts, and to interpret the obtained HER performance for MXenes in the view of corrosion/ structural evolution.

Metal Ion-Induced Porous MXene for All-Solid-State Flexible Supercapacitors

“…Therefore, our goal was to develop easier modification of MXene, i.e., the layer expansion and a morphology of MXene layers with holes, to accelerate the H + intercalation and deintercalation to increase higher capacitance at high rates. MXenes tend to degrade or oxidize slowly overtime, − and we hypothesized that we could exploit and control this breaking of 2D layers to enhance energy storage applications …”

Controlling the Surface Reactivity of Hybrid Ti3CN MXene via In‐situ Electrocatalysis

“…The hybrid Ti 3 CN outperforms the pure phase Ti 3 CN corroborating the −O/−OH functionalization mechanism, as the latter has more −F basal plane coverage due to LiF/H 2 SO 4 chemical etching. This hybrid also outperforms both multilayer Ti 3 C 2 , Ti 4 N 3 , and Ti 2 C, which exhibit overpotentials of −0.66 V, −0.82 V and −0.69 V, respectively (Table S2) [7,11,35] …”

“…This hybrid also outperforms both multilayer Ti 3 C 2 , Ti 4 N 3 , and Ti 2 C, which exhibit overpotentials of À 0.66 V, À 0.82 V and À 0.69 V, respectively (Table S2). [7,11,35] The HER kinetics were probed by acquiring Tafel plots which are presented in Figure 3b. The higher HER performance of the hybrid Ti 3 CN was further corroborated by a lower Tafel slope of 126 mV/decade as compared to the 253 mV/decade and 284 mV/decade for the Ti 3 AlCN and Ti 3 CN, respectively, indicating a Volmer rate determining step (Figure S2, Supplemental Information).…”

“…Current research efforts are being targeted at developing inexpensive, yet active catalysts to drive the HER reaction, with one option being the special class of twodimensional (2D) carbides and nitrides known as MXenes. [4][5][6][7] MXenes are a family of 2D transition metal carbides, nitrides, and carbonitrides which have demonstrated promising electrochemical performance for HER. [8][9][10][11][12][13][14][15][16][17][18][19][20] Their general formula is M n + 1 X n T x (n = 1-4), where M represents an early transition metal (such as Ti, Mo, V, etc.…”

“…However, the high cost and low abundance of Pt hinders the large‐scale commercialization of HER technologies based on Pt/C. Current research efforts are being targeted at developing inexpensive, yet active catalysts to drive the HER reaction, with one option being the special class of two‐dimensional (2D) carbides and nitrides known as MXenes [4–7] …”