Modulating oxygen electronic orbital occupancy of Cr-based MXenes via transition metal adsorbing for optimal HER activity

Zhang, Xilin; Chen, Lu; Sun, Qian; Pang, Yudong; Yang, Xinwei; Yang, Zongxian

doi:10.1016/j.ijhydene.2021.05.075

Cited by 9 publications

(10 citation statements)

References 67 publications

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“…Cr 2 CO 2 and Mo 2 CO 2 not only acted as supports to stabilize TM atoms, but also worked as active sites with anchored TM single atoms to accelerate the HER process. Zhang et al [87] employed a series of TM adatoms to regulate the surface electronic properties of O-terminated Cr-based MXenes. The results showed that both the host metal atoms and the adsorbed TM atoms on Cr-based MXenes could influence the charge transfer of surface O atoms, which played a critical role in modifying the H adsorption strength.…”

Section: Metal Atom Dopingmentioning

confidence: 99%

“…Zhang et al. [ 87 ] employed a series of TM adatoms to regulate the surface electronic properties of O‐terminated Cr‐based MXenes. The results showed that both the host metal atoms and the adsorbed TM atoms on Cr‐based MXenes could influence the charge transfer of surface O atoms, which played a critical role in modifying the H adsorption strength.…”

Section: Defective Mxenes‐based Electrocatalysts For Water Splittingmentioning

confidence: 99%

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MXene Nanoarchitectonics: Defect‐Engineered 2D MXenes towards Enhanced Electrochemical Water Splitting

Tang

Yang

et al. 2022

Advanced Energy Materials

181

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catalysts are currently widely utilized as the best performing HER and OER catalysts, respectively. But their high cost and scarcity seriously hinders their extensive implementation. Therefore, developing cost-effective alternatives and studying the electrocatalytic mechanisms of HER and OER catalysts is of practical significance and is economically desirable.2D transition metal (TM) carbides and nitrides, well-defined MXenes, constitute a thriving layered material family. MXenes are typically synthesized by extracting the "A" layers (A = Si, Al, Ga, etc.) from layered MAX (M n+1 AX n ) precursors. Generally, MXenes are described using the chemical formula M n+1 X n T z , where M refers to TM elements (such as Ti, V, Cr, and Mo); X represents C and/or N; T z stands for O, OH, F, Cl, Br surface terminals; [3,4] and n = 1, 2, 3, or 4. [5,6] In 2016, Seh et al. [7] used theoretical and experimental results to demonstrate that Mo 2 CT x could be an active and stable catalyst for HER, which inspired the blooming development of MXenes-based electrocatalysts. Theoretical predictions have indicated that MXenes are promising electrocatalysts owing to their high electrical conductivity, excellent hydrophilicity, large surface areas, tunable structures, and ultralow work functions. [8][9][10] However, the catalytic activities of most pristine MXenes do not perform well because they restack easily and have poor stability in oxidating environments. It has been proven that catalytic performance 2D MXenes-based nanoarchitectures are being actively explored for electrocatalytic water splitting because they possess physical and physiochemical properties that enhance catalytic activity toward the hydrogen evolution reaction and oxygen evolution reaction. This review systematically summarizes current strategies involved in defect engineering, including introducing atomic vacancies and active edges, and doping with metal and non-metal atoms, which have been employed to achieve high-efficiency MXenes-based catalysts. The electronic structures, optimized adsorption/desorption energies of the intermediates, and possible catalytic mechanisms resulting from various defects are disclosed based on combined experimental results and theoretical calculations. Current challenges and future opportunities for the mechanistic investigation and practical application of defective MXenesbased catalysts are proposed. This report aims to reveal the nature of defective MXenes electrocatalysts and to provide valuable guidelines for designing defective MXenes-based nanoarchitectures for various catalytic reactions.

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Section: Metal Atom Dopingmentioning

confidence: 99%

Section: Defective Mxenes‐based Electrocatalysts For Water Splittingmentioning

confidence: 99%

MXene Nanoarchitectonics: Defect‐Engineered 2D MXenes towards Enhanced Electrochemical Water Splitting

Tang

Yang

et al. 2022

Advanced Energy Materials

181

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“…[ 12 ] predicted the stable existence of Cr 2 TiC 2 T x MXene through DFT calculation, and successfully synthesized Cr 2 TiC 2 T x MXene through experiments that verified the prediction of the DFT results. In particular, it has been shown that Ti atoms can be deposited on a Cr 2 TiC 2 substrate by various techniques such as atomic layer deposition, [ 13 ] electrostatic adsorption, [ 14 ] pyrolysis, [ 15 ] and solution‐phase [ 16 ] method; this stability of the Ti decoration was also found in a recent theoretical paper, [ 17 ] where a single Ti atom on a Cr 2 TiC 2 T x substrate was found to be somewhat more stable on the surface than a Ti metal cluster. These experimental and theoretical developments are the cornerstones of our research.…”

Section: Introductionmentioning

confidence: 79%

“…We constructed a Cr 2 TiC 2 O 2 MXene slab (called “MXene” in the paper) with a primitive lattice constant of 2.80 Å in the x and y directions; it exhibits

P\bar{3}m1

symmetry and is consistent with our previous study. [ 17 ] A single Ti atom was adsorbed on one side of the MXene surface. Three different adsorption sites of the Ti atom on Cr 2 TiC 2 O 2 MXene were considered; the starting sites for the ad‐atom are indicated in Figure S1 (Supporting Information).…”

Section: Systems and Methodsmentioning

confidence: 99%

A New Mars‐van Krevelen Mechanism for CO Oxidation on a Ti‐Decorated MXene

Zhang

Peng

Chen

et al. 2023

Adv Materials Inter

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First‐principles computations are performed to investigate the catalytic oxidation of CO on a Ti‐decorated Cr2TiC2O2 MXene monolayer, through comprehensive analysis of charge transfer, electronic density of states, and charge density difference of the interacting systems. By comparing the reaction energy barriers, it is found that, rather than the traditional Langmuir–Hinshelwood, Eley–Rideal, and Mars‐van Krevelen (MvK) mechanisms, the CO oxidation favours a new variant of the MvK mechanism, in which the anchored Ti atom activates the surface oxygen to spill over from the substrate and take part in the CO oxidation. This work highlights the importance of activating the surface oxygen atoms of MXene by foreign metal atoms to improve the catalytic activity, and suggests that further studies into the new MvK mechanism for CO oxidation may prove worthwhile.

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“…, can effectively modulate the electronic and chemical properties of MXene substrates. 97,176–180 For instance, Ni single atoms anchored on Cr 2 CO 2 (Ni/Cr 2 CO 2 ) resulted in a significant electron transfer from Ni atoms to nearby O on the surface of Cr 2 CO 2 , making these O atoms favourable for HER. 181 Transition metals on Ti-based MXenes (Ti 2 CO 2 , Ti 3 C 2 O 2 , and Ti 3 CNO 2 ) can induce electron redistribution, making either transition metals or surficial O atoms as catalytic sites for HER.…”

Section: Electrochemical Conversion Reactionsmentioning

confidence: 99%

Engineering strategies and active site identification of MXene-based catalysts for electrochemical conversion reactions

et al. 2023

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Modulating oxygen electronic orbital occupancy of Cr-based MXenes via transition metal adsorbing for optimal HER activity

Cited by 9 publications

References 67 publications

MXene Nanoarchitectonics: Defect‐Engineered 2D MXenes towards Enhanced Electrochemical Water Splitting

MXene Nanoarchitectonics: Defect‐Engineered 2D MXenes towards Enhanced Electrochemical Water Splitting

A New Mars‐van Krevelen Mechanism for CO Oxidation on a Ti‐Decorated MXene

Engineering strategies and active site identification of MXene-based catalysts for electrochemical conversion reactions

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