Vacancy‐Rich MXene‐Immobilized Ni Single Atoms as a High‐Performance Electrocatalyst for the Hydrazine Oxidation Reaction

Abstract

Single‐atom catalysts (SACs), on account of their outstanding catalytic potential, are currently emerging as high‐performance materials in the field of heterogeneous catalysis. Constructing a strong interaction between the single atom and its supporting matrix plays a pivotal role. Herein, Ti3C2Tx‐MXene‐supported Ni SACs are reported by using a self‐reduction strategy via the assistance of rich Ti vacancies on the Ti3C2Tx MXene surface, which act as the trap and anchor sites for individual Ni atoms. The constructed Ni SACs supported by the Ti3C2Tx MXene (Ni SACs/Ti3C2Tx ) show an ultralow onset potential of −0.03 V (vs reversible hydrogen electrode (RHE)) and an exceptional operational stability toward the hydrazine oxidation reaction (HzOR). Density functional theory calculations suggest a strong coupling of the Ni single atoms and their surrounding C atoms, which optimizes the electronic density of states, increasing the adsorption energy and decreasing the reaction activation energy, thus boosting the electrochemical activity. The results presented here will encourage a wider pursuit of 2D‐materials‐supported SACs designed by a vacancy‐trapping strategy.

Supercritical CO2-assisted solid-phase etching preparation of MXenes for high-efficiency alkaline hydrogen evolution reaction

“…Based on the above characterization, the reaction of Ti MXenes are promising electrocatalysts owing to their large surface areas, high electrical conductivity, ultralow work functions, tunable structures, and excellent hydrophilicity, which have been already confirmed by theoretical predictions. 35,36 In addition, it has been reported that the metallic MXene nanosheets with rich surface -F groups exhibit highly efficient and stable HER electrocatalytic properties, 37 which can not only lower the charge-transfer resistance, but also reinforce the proton adsorption kinetics. 37 Thus, the achieved 2D SC CO 2 -Ti 3 C 2 T x loaded with Pt clusters (SC CO 2 -Ti 3 C 2 T x -Pt) was investigated to construct an alkaline hydrogen evolution electrocatalyst using a standard three-electrode system within an alkaline electrolyte (1.0 M KOH).…”

Recent Advances and Perspectives of Lewis Acidic Etching Route: An Emerging Preparation Strategy for MXenes

“…Additionally, MXenes have been widely utilized to support metal or metal compounds. Based on the excellent synergistic effect between MXenes and metals or metal compounds, MXenes/metals hybrids and MXenes/metal compounds composites exhibit better performance than their individual components and have been widely investigated in various fields [54,73,[134][135][136][137][138]. Nevertheless, the traditional fabrication process of MXenes/ metals hybrids or MXenes/metal compounds composites usually requires the synthesis of MXenes and the subsequent introduction of additional metal sources, which makes the preparation process complicated [117,[139][140][141][142][143][144].…”

The synthesis of single-atom catalysts for heterogeneous catalysis

“…The asymmetric coordination environment in Co–N 4 P increased the C-H bond cleavage of HCOO* via the reduction of the energy barrier and boosted proton adsorptions to accelerate the fast generation of H 2 in Co–N 4 P. The as-made 5.3 wt% Co–N 4 P possessed an impressive mass activity (4285.6 mmol g −1 h −1 ) with 100% selectivity and outstanding stability toward the dehydrogenation of formic acid at 80 °C, which was 5.0, 25.5, and 23.1 times that of symmetrically coordinated Co–N 4 , commercial Pd/C and Pt/C, respectively. In addition, SACs presented an excellent catalytic performance in hydrazine oxidation reaction, 124 silane oxidation with water, 125 oxidative desulfurization, 126,127 and other reactions. 128–130 The catalytic performance for different organic reactions over SACs is outlined in Table 2 with SACs types, catalytic types, metal loading and so on.…”