Applications In Heterogeneous Catalysis Research Articles

Emerging Ultrahigh‐Density Single‐Atom Catalysts for Versatile Heterogeneous Catalysis Applications: Redefinition, Recent Progress, and Challenges

In recent years, single‐atom catalysts (SACs) with high metal loading have emerged in different heterogeneous catalysis fields and shown extraordinary catalytic properties. When there are enough coordination atoms (or functional groups) on the supports, it is possible to achieve a limit monolayer atom loading on the surface of supports with ultrahigh atom density (5–15 atoms nm−2) and extremely close site distance (0.2–0.5 nm), by using appropriate synthesis methods and procedures. These high‐density metal atoms usually have no or less metal bonds, which are mostly isolated by support atoms to form 3D foam‐like atomic constructions. Herein, a new notion of metal atomic foam catalysts (AFCs) is propsed to redefine these ultrahigh‐density SACs accommodated by specific supports. This new paradigm of 3D atomic construction for SACs has potential significance for both theoretical research and industrial applications. The latest major advancements in the controllable synthesis of AFCs on various supports (e.g., polymer, carbon, and metallic compound) via different methods (bottom‐up or top‐down approaches) are summarized. The latent catalytic principles and typical application cases of AFCs are emphasized in a wide range of heterogeneous catalysis fields (e.g., thermocatalysis, photocatalysis, electrocatalysis, etc.). The challenges and prospects of this newly 3D ultrahigh‐density AFCs materials in practical industrial application are pointed out as well.

Nickel supported on magnetic biochar as a highly efficient and recyclable heterogeneous catalyst for the one‐pot synthesis of spirooxindole‐dihydropyridines

AbstractMagnetic materials show promising applications in heterogeneous catalysis because of their ease of separation and good reusability. The present work reports the design, synthesis, and characterization of a novel magnetic biochar supported nickel catalyst. Fourier infrared spectroscopy (FT‐IR), powder X‐ray diffraction technology (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and vibrating sample magnetometer (VSM) techniques were used for analyzing the prepared catalyst. The prepared catalyst exhibited excellent catalytic activity for synthesis of spirooxindole‐dihydropyridines derivatives by a one‐pot three‐component reaction of isatin, barbituric acid, and 6‐amino uracil or 1H‐pyrazol‐5‐amine. This new methodology demonstrated some important features, including high yields, lower loading of the catalyst, easy work‐up, and recyclability of the catalyst for a minimum of six times without an obvious decay of catalytic performance.

Boron: A key functional component for designing high-performance heterogeneous catalysts

Heterogeneous catalysis is a vivid branch of traditional catalysis field, with the advantage of high efficiency and being easily separated from reactants and products after reaction, and have received widespread attentions in large-scale industrial production, especially in the field of energy utilization. Boron has been found to be a key functional component for designing high-performance heterogeneous catalysts. In this review, we cover and categorize the past and recent progress in boron-containing materials and their applications in heterogeneous catalysis particularly in energy‐related fields. The fundamental roles of boron components in the emerging heterogeneous catalysis of construction, regulation and stabilization of active phases/sites are highlighted, with the emphasis on how they regulating structural and electronic properties of host materials. We then categorize boron-containing catalysts into six kinds mainly including intermetallic boride catalysts, metal boride-derived catalysts, boron-doped catalysts, metal boride-decorated catalysts, boron-containing compounds as catalyst supports, and single-boron-site catalysts, as well as try to establish structure-catalytic activity relationship. The catalytic applications of these six boron-containing catalysts are discussed separately, focusing on the energy-related reactions such as hydrogen evolution reaction (HER), oxygen evolution reaction (OER), oxygen reduction reaction (ORR), carbon dioxide reduction reaction (CO2RR) and nitrogen reduction reaction (NRR). Finally, the opportunities and challenges related to boron-containing compounds in the field of catalysis are prospected.

Enhanced photostability in protonated covalent organic frameworks for singlet oxygen generation

•Enhanced photostability of vinylene-linked COFs by protonation treatment •Specific mechanism for enhanced photostability by theoretical calculation •Extensive visible light absorbance and facilitated photocarrier separation •Boosted singlet oxygen generation and its detailed production mechanism Covalent organic frameworks (COFs), highly ordered, functional porous crystalline polymers, have found prospective applications in heterogeneous catalysis. Owing to unique fully π-conjugated sp2 carbon structures, vinylene-linked CO-Fs provide an extraordinary platform to develop photocatalysis, while they suffer from serious photo-instability during catalysis, hindering widespread applications. Here, by taking g-C18N3-COF as a prototypical system, we propose that protonation endows it with enhanced photostability by impeding the flow of band electrons, meanwhile light absorption was extended to long wavelength and separation of photocarriers is facilitated. Both structural and spectroscopic results demonstrated the greatly improved photostability of protonated g-C18N3-COF, which can keep the vinylene-linked framework for a long time under visible light irradiation. Benefiting from the above merits, the protonated g-C18N3-COF was an efficient catalyst for singlet oxygen generation by two sequential charge transfer processes. This work provides a practical approach to enhance the photostability and catalytic activities of vinylene-linked CO-Fs and its derivatives. Covalent organic frameworks (COFs), highly ordered, functional porous crystalline polymers, have found prospective applications in heterogeneous catalysis. Owing to unique fully π-conjugated sp2 carbon structures, vinylene-linked CO-Fs provide an extraordinary platform to develop photocatalysis, while they suffer from serious photo-instability during catalysis, hindering widespread applications. Here, by taking g-C18N3-COF as a prototypical system, we propose that protonation endows it with enhanced photostability by impeding the flow of band electrons, meanwhile light absorption was extended to long wavelength and separation of photocarriers is facilitated. Both structural and spectroscopic results demonstrated the greatly improved photostability of protonated g-C18N3-COF, which can keep the vinylene-linked framework for a long time under visible light irradiation. Benefiting from the above merits, the protonated g-C18N3-COF was an efficient catalyst for singlet oxygen generation by two sequential charge transfer processes. This work provides a practical approach to enhance the photostability and catalytic activities of vinylene-linked CO-Fs and its derivatives.

Supported nanocatalysts: recent developments in microwave synthesis for application in heterogeneous catalysis

MW-assisted synthesis enhanced the catalytic properties of supported nanocatalysts, which is desirable for industrial applications. However, the wide variations and complexities in MW methods need to be simplified, as demonstrated in the graphic.

Stabilization of Exposed Metal Nanocrystals in High-Temperature Heterogeneous Catalysis.

Colloidal metal nanocrystals with uniform sizes, shapes, compositions, and architectures are ideal building blocks for constructing heterogeneous catalysts with well-defined characteristics toward the investigation of accurate structure-property relationships and better understanding of catalytic mechanism. However, their applications in high-temperature heterogeneous catalysis are often restricted by the difficulty in maintaining the high metal dispersity and easy accessibility to active sites under harsh operating conditions. Here, a partial-oxide-coating strategy is proposed to stabilize metal nanocrystals against sintering and meanwhile enable an effective exposure of active sites. As a proof-of-concept, controlled partial silica coating of colloidally prepared Pd0.82 Ni0.18 nanocrystals with the size of 8 nm is demonstrated. This partially coated catalyst exhibits excellent activity, selectivity, and stability, outperforming its counterparts with fully coated and supported structures, in reverse water gas shift (RWGS) catalysis particularly at high operating temperatures. This study opens a new avenue for the exploration of colloidal metal nanocrystals in high-temperature heterogeneous catalysis.

Zeolitic imidazolate framework (ZIF-8)/polyacrylonitrile derived millimeter-sized hierarchical porous carbon beads for peroxymonosulfate catalysis

Well dispersed nanocatalysts on porous substrate with macroscopic morphology are highly desired for the application of heterogeneous catalysis. Traditional fabrication process suffers from multiple steps for controlling the structure on nanocatalysts and matrix or both. Herein, we report a facile strategy for the synthesis of millimeter-sized hierarchical porous carbon beads (HPCBs) which containing well dispersed hollow-nano carbon boxes for peroxymonosulfate catalysis. Specially, the precursors of HPCBs were prepared by phase inversion method, which involving introduction of zeolitic imidazolate framework (ZIF-8) nanocubes into polyacrylonitrile (PAN) solutions followed by solidification of the mixture. After pyrolysis, nitrogen doped and hierarchical porous HPCBs with diameter of about 1.2 mm were obtained. The merits of our synthesis strategy lie in that synchronizes the hollow microstructure evolution with the shaping of ZIF-8 nanocubes into millimeter scale beads. Attribute to its special structure feature and the appropriate chemical composition, the resultant millimeter-sized HPCBs exhibit enhanced catalytic performance by activation of peroxymonosulfate (PMS) for tetracycline degradation. The degradation efficiency of TC is up to 85.1% within 120 min, which is 18% higher than that of ZIF8-Solid/PAN carbon bead (SPCBs). In addition, the possible decomposition pathways, main reactive oxygen species, and reasonable enhanced mechanism for the HPCBs/PMS system are systematically investigated by quenching experiments, electron paramagnetic resonance (EPR) and liquid chromatography-mass spectrometry (LC-MS). This work addresses the issue of easy aggregation and recycling of carbon materials in industrial productions and extends the prospects of carbon materials in engineering applications.

Toward the Continuous Production of Multigram Quantities of Highly Uniform Supported Metallic Nanoparticles and Their Application for Synthesis of Superior Intermetallic Pt-Alloy ORR Electrocatalysts.

A fast and facile pulse combustion (PC) method that allows for the continuous production of multigram quantities of high-metal-loaded and highly uniform supported metallic nanoparticles (SMNPs) is presented. Namely, various metal on carbon (M/C) composites have been prepared by using only three feedstock components: water, metal–salt, and the supporting material. The present approach can be elegantly utilized also for numerous other applications in electrocatalysis, heterogeneous catalysis, and sensors. In this study, the PC-prepared M/C composites were used as metal precursors for the Pt NPs deposition using double passivation with the galvanic displacement method (DP method). Lastly, by using thin-film rotating disc electrode (TF-RDE) and gas-diffusion electrode (GDE) methodologies, we show that the synergistic effects of combining PC technology with the DP method enable production of superior intermetallic Pt–M electrocatalysts with an improved oxygen reduction reaction (ORR) performance when compared to a commercial Pt–Co electrocatalyst for proton exchange membrane fuel cells (PEMFCs) application.

Bio-Templating: An Emerging Synthetic Technique for Catalysts. A Review

In the last few years, researchers have focused their attention on the synthesis of new catalyst structures based on or inspired by nature. Biotemplating involves the transfer of biological structures to inorganic materials through artificial mineralization processes. This approach offers the main advantage of allowing morphological control of the product, as a template with the desired morphology can be pre-determined, as long as it is found in nature. This way, natural evolution through millions of years can provide us with new synthetic pathways to develop some novel functional materials with advantageous properties, such as sophistication, miniaturization, hybridization, hierarchical organization, resistance, and adaptability to the required need. The field of application of these materials is very wide, covering nanomedicine, energy capture and storage, sensors, biocompatible materials, adsorbents, and catalysis. In the latter case, bio-inspired materials can be applied as catalysts requiring different types of active sites (i.e., redox, acidic, basic sites, or a combination of them) to a wide range of processes, including conventional thermal catalysis, photocatalysis, or electrocatalysis, among others. This review aims to cover current experimental studies in the field of biotemplating materials synthesis and their characterization, focusing on their application in heterogeneous catalysis.

Thermoelastic modeling of laser-induced generation of strong surface acoustic waves

Short pulse laser irradiation of a substrate can generate pulses of surface acoustic waves (SAWs) capable of propagating long distances along the surface of the irradiated substrate. In this work, we use thermoelastic modeling of the generation of SAWs on a Si substrate to explore the effect of irradiation parameters, i.e., pulse duration, laser spot size, absorption depth, and spatial profile of the laser energy deposition, on the strength of the SAWs. A particular goal of this study is to establish the optimum conditions for maximizing the strength of the surface waves generated in the nonablative, thermoelastic irradiation regime. The simulations demonstrate that the highest strain amplitude of the laser-generated SAWs can be achieved for a laser spot size comparable to the characteristic length of the SAW propagation during the laser pulse. The amplitude of SAWs increases with the increase in the characteristic laser energy deposition depth, and laser pulses with sharper spatial energy deposition profiles (flat-top laser beams) produce stronger SAWs. For the optimal set of irradiation parameters, the strain amplitude of a SAW generated in Si in the thermoelastic regime can reach the levels of 10−4–10−3, which are sufficiently high for causing nonlinear sharpening of the wave profile and the formation of a shock front during the wave propagation from the laser spot. The computational predictions suggest the feasibility of a continuous generation of strong nonlinear pulses of SAWs, which may be utilized for driving the surface processes in thin film deposition, growth of two-dimensional materials, heterogeneous catalysis, and other applications.

Double Lamellar Morphologies and Odd–Even Effects in Two- and Three-Dimensional N,N′-bis(n-alkyl)-naphthalenediimide Materials

The fabrication of highly ordered nanostructured surfaces is desirable in supramolecular chemistry and envisaged to bolster advances in heterogeneous catalysis and microelectronic applications. Here, we report on a novel set of alkylated double N,N′-bis(n-alkyl)-naphthalenediimides (NDIs) for the functionalization of highly oriented pyrolytic graphite (HOPG) with precise double lamellar morphologies. A detailed analysis of the two-dimensional (2D) self-assembled monolayers by scanning tunneling microscopy (STM) reveals that the structural repeating unit of the double lamellae is tuned precisely by the length of the alkyl chain that is connecting the NDI units. However, the expected odd–even effect is disturbed within the monolayers of a series of homologues. In contrast, a clear odd–even effect is observed for the melting temperatures of the respective bulk materials. Small-angle X-ray scattering reveals that these bulk materials exhibit nanophase-separated lamellar phases with domain spacings that are slightly larger than the repeating units of the double lamellar structures formed on the HOPG surface. The discrepancy is assigned to a partial desorption of the alkyl spacer from the HOPG surface, which becomes more pronounced when increasing its length. Our findings suggest that this lengthening increases the conformational freedom of the molecules on the surface while retaining a double lamellar morphology.

Physical Properties of Cyclic Esters and its Application in Heterogeneous Electrocatalysis

Oxygen reduction is a key reaction in many energy conversion devices. Phosphorus-containing porous organic polymers not only have developed pores and surface structure, but also have strong adjustable modification and modification, so they have a wide application prospect in heterogeneous catalysis. At present, the preparation of phosphorus-containing porous organic polymers and their applications in heterogeneous catalysis have not been reviewed. in this paper, the research progress in this field in the past decade is summarized and reviewed. The synthetic methods of phosphorus-containing porous organic polymers are developing rapidly, including coupling Polycondensation, lithium salt-mediated Polycondensation, Friedel-Crafts Polycondensation, solvothermal olefin polymerization, Scholl Polycondensation, phenolic polymerization, aldehyde-amine condensation, phosphorization of polypyran salts and multistage polymerization. At the same time of briefly describing the mechanism of oxygen reduction reaction, combined with the research results of my own team, this paper focuses on the application of new porous materials (metal-organic framework MOF, conjugated microporous polymer CMP, etc.) in electrocatalysis. In view of the problems existing in the current electrocatalysts, the future research ideas are pointed out, including the use of advanced technical means to characterize the active sites of the catalysts in situ, based on the fact that there are a large number of phosphine ligands in the framework, phosphorus-containing porous organic polymers can be loaded with a series of metal compounds to make supported metal nanoparticles catalysts, or even monoatomic or unit point metal catalysts. The optimal structure of the catalyst was inversely calculated from the high active sites, and the preparation conditions of the materials were optimized. Under the guidance of theory and practice, a new type of electrocatalyst with high efficiency, stability, economy and environmental protection was developed on the premise of in-depth understanding of the mechanism of oxygen reduction reaction. Then an example is given to introduce the use of POPs to solve the basic scientific problems related to biomimetic catalysis, and show its great application potential. Finally, the challenges and opportunities in this emerging field are summarized and put forward.

Developed Nanomaterials with a Pdcore-Fe-Pdskin Structure for Efficient Electrocatalytic Performance in Oxygen Reduction and Glycerol Oxidation Reactions in Alkaline Electrolytes

One of the unsolved important fundamental and applied questions in heterogeneous electrocatalysis for low-temperature fuel cells and electrolyzers is about our ability to engineer a unique electrocatalyst that can simultaneously operate for both anode and cathode without changing the composition/structure or the synthesis method. Our present contribution is about a solution in the case of iron-diluted Pd nanoparticles. ORR is the common bottleneck of the pollution-free electricity production with alkaline technologies of rechargeable metal-air batteries and fuel cells. As alternative to scarcely Pt, Pd-based materials have attracted much attention for different applications in heterogeneous catalysis and not only for ORR, but also for glycerol (biomass-based byproduct) oxidation that is also common reaction (anode) for fuel cells and low-energy input electrolyzers to produce green H2. So, being able to prepare a nanocatalyst that is simultaneously active and durable for both ORR and glycerol oxidation reaction (GOR) is highly desired. We observed that the support plays an important role and the presence of Fe (20%) dramatically improves the performance. The developed bimetallic PdFe performed efficiently and selectively ORR in alkaline media at the maximum faradaic yield of four-electron transfer (100%) and high kinetic current density j k of 2 mA cm−2 Pd (1 A mg−1 Pd) at 0.9 VRHE, which largely exceeds the tested commercial Pd/C and the literature. For glycerol electrooxidation, the obtained peak current density of j p = 2.3 mA cm−2 Pd (1.1 A mg−1 Pd) and faradaic efficiency of FE = 83-99% outperformed the commercial Pd/C (j p = 0.47 mA cm−2 Pd (0.39 A mg−1 Pd, FE = 78%) and the majority of the reported catalysts.Our conducted DFT calculations reveal that the high performance of the bimetallic PdFe arises from a unique structure with Pd in the core plus skin and Fe in the second layer. This particular configuration of skin surfaces has been reported for PtNi to trigger high electrocatalytic kinetics for ORR. Those findings open new possibilities in the development of multifunctional nanocatalysts for the sustainable electrochemical energy conversion and storage Figure 1

Clariant doubles output of emission control catalyst

This work focuses on designing highly-porous cellular NiAl2O4-based spinel ceramics through combined suspension emulsification/reactive sintering and further decoration of the pore surfaces by Ni nanoparticles for potential applications in heterogeneous catalysis. Due to kinetic limitations and specific porous structure, the reduction occurs without affecting the integrity of the cellular monoliths. The reaction mechanism, assessed by XRD and TEM/EDS, includes both partial decomposition and reduction, resulting in the formation of metastable Al-enriched phases, mainly NiAl32O49, and metallic Ni phase, respectively. The results suggest that the cellular bulk framework can be decorated with Ni catalyst in a controlled way, by proper selection of the initial cation stoichiometry of the NiAl2O4 spinel and appropriate reduction conditions. In selected conditions the reduction results in Ni nanoparticles of various dimension scales, finely dispersed at the pore surfaces, with a significant fraction below 50 nm, as confirmed by TEM/EDS. The results of thermodynamic analysis emphasize that the redox tolerance of the spinel phase is dependent on the Ni:Al activity ratio, suggesting the prospects for tuning the catalytic activity and stability by designing the initial composition and resulting content of metallic Ni and Ni- and Al-containing metastable phases.

Highly efficient catalytic reduction of 4-nitrophenol and organic dyes by ultrafine palladium nanoparticles anchored on CeO2 nanorods.

Uniformly dispersed Pd nanoparticles on certain supports exhibit exceptional catalytic performance toward various environmental applications. In this work, ultrafine Pd nanoparticles anchored on CeO2 nanorods were synthesized via an absorption-in situ reduction method. The activity of the CeO2/Pd nanocomposites was systematically investigated toward reduction of 4-nitrophenol (4-NP) and organic dyes including methyl blue, rhodamine B, methyl orange, and Congo red. The results indicated that the CeO2/Pd nanocomposites with different weight ratios of Pd nanoparticles (10.23 wt%, 11.01 wt%, and 14.27 wt%) can almost completely reduce 4-NP with a rate constant of 3.31×10-1, 3.22×10-1, and 2.23×10-1 min-1. Besides, the 10.23 wt% CeO2/Pd nanocomposites exhibit remarkable enhanced catalytic activity toward reduction of organic dyes. The catalysts display ideal stability after being used for three times for the reduction of 4-NP. We believe that our strategy demonstrated here offers insights into the design and fabrication of novel Pd-based nanocomposites for various heterogeneous catalysis applications.

Defect Engineering on CeO2‐Based Catalysts for Heterogeneous Catalytic Applications

With abundant crystal defects, cerium oxide (CeO2), widely used in heterogeneous catalysis, has attracted extensive attention. In recent years, researchers have investigated that the defect chemistry of CeO2 plays a vital role in its catalytic activity and have developed various defect introduction methods to synthesize stable and efficient defective CeO2‐based catalysts. Herein, the understanding, introduction, and applications of defect chemistry in CeO2‐based heterogeneous catalysis are reviewed, and the structure–activity relationship between defect engineering and catalytic performance is recommended with great emphasis. Interests are put into the investigation of how defects influence the activity and stability of defective CeO2 catalysts and effective strategies for fabricating efficient, stable, and defective CeO2 catalysts. Finally, the existing problems and perspectives of CeO2 defect chemistry for heterogeneous catalysis are displayed. This review provides a reference for in‐depth understanding and the design of more efficient CeO2‐based catalysts for heterogeneous catalysis.

Design of compositionally complex catalysts: Role of surface segregation

Besides revealing excellent mechanical properties, compositionally complex alloys are also very promising candidates for applications in heterogeneous catalysis. The opportunity provided by the tremendously large composition phase space to explore new materials and tune the materials properties in the materials design cycle is, however, intrinsically coupled with the challenge of controlling surface segregation, which is generally more severe in multicomponent alloys as compared to simpler systems. We demonstrate this by computing the surface phase diagram of two candidate compositionally complex catalysts. Significant surface segregation is found even at very high temperature and this can strongly affect the catalytic properties of these alloys. We explain the observed phase stabilities in terms of segregation energies and rationalize the segregation trends with canonical models. Finally, we propose a set of descriptors accessible with first-principles calculations that allows to quickly incorporate the evaluation of the segregation during the alloy design process.

Ruthenium Supported on Cobalt‐Embedded Porous Carbon with Hollow Structure as Efficient Catalysts toward Ammonia‐Borane Hydrolysis for Hydrogen Production

AbstractCatalysts with high activity play an indispensable role in ammonia‐borane (AB) hydrolysis for hydrogen production. Supported catalysts are always used because proper support can effectively prevent metal particle agglomeration. In addition, the interaction between support and metal species can further enhance the catalytic activity. Herein, cobalt‐embedded porous carbon with polyhedral structure (CoPCP) is successfully synthesized by one‐step carbonization of a core‐shell structured ZIF‐8@ZIF‐67 composite. As support, Ru nanoparticles are loaded on CoPCP by in situ reduction to obtain Ru/CoPCP catalysts with a special hollow structure, effectively preventing Ru nanoparticles from agglomeration. Moreover, the existence of synergistic effect between Co metal and Ru nanoparticles in Ru/CoPCP catalyst is confirmed by a series of well‐designed control experiments. Both these factors endow the Ru/CoPCP catalyst with high activity and decent stability toward AB hydrolysis. A low activation energy (Ea = 31.25 kJ mol–1) and a high catalytic performance (turnover frequency = 243.4 molH2 molRu–1 min–1) are simultaneously achieved for Ru1/CoPCP‐1000 even with a low amount of Ru (1.88 wt%). This work represents a promising method to prepare the high‐activity catalysts with low content of noble metals for diverse applications in heterogeneous catalysis.

Adsorption of Carbon Dioxide on Mono-Layer Thick Oxidized Samarium Films on Ni(100).

Studies of adsorption of CO on nanoscopic surfaces are relevant for technological applications in heterogeneous catalysis as well as for sorption of this important greenhouse gas. Presently, adsorption of carbon dioxide on pure and oxidized thin samarium layers near mono-layer thickness on Ni(100) has been investigated by photoelectron spectroscopy and temperature programmed desorption. It is observed that very little CO adsorb on the metallic sample for exposures in the vacuum regime at room temperature. For the oxidized sample, a large enhancement in CO adsorption is observed in the desorption measurements. Indications of carbonate formation on the surface were found by C 1s and O 1s XPS. After annealing of the oxidized samples to 900 K very little CO was found to adsorb. Differences in desorption spectra before and after annealing of the oxidized samples are correlated with changes in XPS intensities, and with changes in sample work function which determines the energy difference between molecular orbitals and substrate Fermi level, and thus the probability of charge transfer between adsorbed molecule and substrate.

Unveiling the Interfacial and Structural Heterogeneity of Ti3C2Tx MXene Etched with CoF2/HCl by Integrated in Situ Thermal Analysis.

Ti3C2Tx MXene is a member of the recently discovered two-dimensional early transition metal carbide and nitride family of MXenes with potential applications in energy storage and heterogeneous catalysis at elevated temperatures. Here, we apply a suite of in situ techniques to probe Ti3C2Tx MXene's thermal evolutions, including in situ X-ray diffraction (XRD), in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and integrated thermogravimetry-differential scanning calorimetry-mass spectrometry (TG-DSC-MS). In light of this set of in situ investigations, we find heterogeneity in the layering of Ti3C2Tx MXene revealed only at higher temperatures. Our findings present behavior up to 600 °C, particularly interlayer water and -OH surface end-capping groups. In one group of layers, their interlayer spacing shrinks as water deintercalates, but the other group of layers unexpectedly shows no change in the interlayer spacing. This is strong evidence that intercalants act as guest pillaring agents in the latter layering group, which stabilize these layers at higher temperatures while keeping the interlayer space accessible.