The Passive Effect of MXene on Electrocatalysis: A Case of Ti₃C₂T_x/CoNi−MOF nanosheets for Oxygen Evolution Reaction

Abstract

Herein, CoNi bimetallic metal‐organic framework nanosheets (CoNi−MOFNs) in‐situ grown on Ti3C2Tx MXene (CoNi−MOFNs@MX) were explored as a typical nanocomposite to study the impact of MXene on the electrocatalytic activity of MOF for oxygen evolution reaction (OER). In contrast to previous reports, we observed a passive effect of Ti3C2Tx MXene on the OER performance of CoNi−MOFNs although the electronic conductivity of the nanocomposites was improved. The combined analysis of electrochemical results and atomic valence state characterization demonstrates that the decreased OER activity is likely ascribed to the unfavorable electron donation from Ti3C2Tx MXene, which suppresses the formation of active species for OER from the oxidation of Co2+ and Ni2+ to higher valence states in the nanocomposite. Consequently, more attention needs to be paid to the rational design of nanocomposites with MXenes for electrocatalytic applications.

Grain Boundary Engineering with Cl-Terminated Ti2C Quantum Dots for Enhancing Perovskite Solar Cell Performance

“…Fourier transform infrared spectroscopy (FTIR) is utilized to figure out the surface groups of the Ti 2 C QDs. As depicted in Figure c, the bonding structures of C–O/CO, Ti–C, Ti–O, and Ti–Cl groups were identified. − X-ray photoelectron spectroscopy (XPS) data presented in Figure d–f demonstrate the appearance of Ti, C, O, and Cl elements, which is in accord with the FTIR analyses. Specifically, the Ti/C ratio is calculated as ∼2, consistent with that of the raw material Ti 2 AlC.…”

Highly Accessible Co–Nx Active Sites-Doped Carbon Framework with Uniformly Dispersed Cobalt Nanoparticles for the Oxygen Reduction Reaction in Alkaline and Neutral Electrolytes

“…Both pyridine N and graphite N coordinate with Co to form Co–N x molecules, and the nitrogen atoms are stabilized in the carbon matrix through the formation of Co–N bonds, which are progressively lost once the cobalt nanoparticles are aggregated because the remaining N–C bonds cannot effectively bind the carbon atoms without the presence of Co–N bonds. , Considering that the valence state of the Co element is significant for the electrochemical performance of the sample, the peak deconvolution of Co 2p for all samples is displayed in Figure d. Two main peaks at 780.8 and 796.7 eV could be attributed to Co 2+ , while peaks centered at 778.6 and 794.2 eV suggest the presence of Co 0 . − There were also only Co 2+ and Co 0 valence states for samples carbonized under diverse temperatures, as shown in Figure S4d. The accurate Co contents of samples were obtained through the ICP test.…”

Metal-organic coordination networks on a titanium carbide MXene: DFT based grand canonical Monte Carlo simulation

“…The synthesized hybrid catalysts show high activity in OER and NRR reactions. A negative effect of the MXene surface in the hybrid Co,Ni-MOF/MXene catalysts on the catalytic activity in OER is also observed [45]. Since the chemical environment of the metal center in the hybrid catalyst remains practically unchanged, the authors believe that the reduced OER activity of the material is associated with the electron-donor properties of the MXene.…”