Tunable Structured MXenes With Modulated Atomic Environments: A Powerful New Platform for Electrocatalytic Energy Conversion

Abstract

Owing to their rich surface chemistry, high conductivity, tunable bandgap, and thermal stability, structured 2D transition‐metal carbides, nitrides, and carbonitrides (MXenes) with modulated atomic environments have emerged as efficient electrochemical energy conversion systems in the past decade. Herein, the most recent advances in the engineering of tunable structured MXenes as a powerful new platform for electrocatalytic energy conversion are comprehensively summarized. First, the state‐of‐the‐art synthetic and processing methods, tunable nanostructures, electronic properties, and modulation principles of engineering MXene‐derived nanoarchitectures are focused on. The current breakthroughs in the design of catalytic centers, atomic environments, and the corresponding structure–performance correlations, including termination engineering, heteroatom doping, defect engineering, heterojunctions, and alloying, are discussed. Furthermore, representative electrocatalytic applications of structured MXenes in energy conversion systems are also summarized. Finally, the challenges in and prospects for constructing MXene‐based electrocatalytic materials are also discussed. This review provides a leading‐edge understanding of the engineering of various MXene‐based electrocatalysts and offers theoretical and experimental guidance for prospective studies, thereby promoting the practical applications of tunable structured MXenes in electrocatalytic energy conversion systems.

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

“…The electrocatalytic NRR has attracted intensive attention as a green method to produce NH 3 at room temperature and atmospheric pressure [242]. Nevertheless, promising electrocatalysts with superior stability and high activity are also required to promote the NRR process, which suffers from a large overpotential and low yield of NH 3 owing to the strong N≡N bond in N 2 [243]. For example, Wang et al prepared highly dispersed Fe immobilized in fluorine-free Ti 3 C 2 T x MXene (HD-Fe-MXene) as NRR electrocatalyst in 0.1 M Na 2 SO 4 electrolyte through FeCl 2 etching and HCl washing (Fig.…”

Tunable Structured Metal Oxides for Biocatalytic Therapeutics

“…In recent years, Yan and other researchers have proposed standardized assays for the determination of catalytic activity and kinetics of biocatalysts, based on which different biocatalysts can be quantified and compared via the calculated dynamic parameters, such as V 0 (the initial rate), V max (maximum formation rate per minute), K m (Michaelis Menten constant, indicating affinity to special substrates), and TON (turnover number, the maximum number of conversed substrates of per unit catalytic active site). [33][34][35][36] The catalytic kinetics of biocatalysts are generally fitted in the Michaelis−Menten kinetic model, whereby plotting the catalytic rate versus substrate concentration, K m and V max can be obtained. The stable state kinetic study provides a convenient but authorized way to compare and assess the catalytic activities of various metal oxides-based biocatalysts.…”

Metal Alloys‐Structured Electrocatalysts: Metal–Metal Interactions, Coordination Microenvironments, and Structural Property–Reactivity Relationships

“…[ 7–10 ] To realize the electrocatalysis conversion processes, lots of solutions have been proposed for fabricating highly efficient transition‐metal catalysts that feature outstanding activities, excellent durabilities, and affordable costs. [ 11–15 ] Among them, benefiting from the unique electronic properties, compositional flexibility, chemical bifunctionality, and long‐term durability, the metal alloys‐structured electrocatalysts (MAECs) have made essential contributions to accelerating the practical applications of electrocatalytic devices in renewable energy systems ( Figure ). [ 16–19 ]…”

“…[7][8][9][10] To realize the electrocatalysis conversion processes, lots of solutions have been proposed for fabricating highly efficient transition-metal catalysts that feature outstanding activities, excellent durabilities, and affordable costs. [11][12][13][14][15] Among them, benefiting from the unique electronic properties, compositional flexibility, chemical bifunctionality, and long-term durability, the metal alloys-structured electrocatalysts (MAECs) have made essential contributions to accelerating the practical applications of electrocatalytic devices in renewable energy systems (Figure 1). [16][17][18][19] The MAECs that were alloying with different elements can potentially create enormous possibilities for structure regulations and inter-site synergistic effects due to the interplay of metalmetal bonds, [20] which originates from the electron perturbation and orbital hybridization between correlated metal species.…”