Calcination Treatment Research Articles

Facile Synthesis of Fe‐Doped CoO Nanotubes as High‐Efficient Electrocatalysts for Oxygen Evolution Reaction

Developing high‐performance, low‐cost, and robust electrocatalysts is of great importance to boost the efficiency of oxygen evolution reaction (OER). Herein, based on the integrated design of chemical composition and geometric structure, Fe‐doped CoO nanotubes (NTs) with high OER activity are prepared by a facile template‐free approach. The construction of this tubular structure is realized via a simple wet‐chemical reaction to prepare solid nanorods as precursor and a subsequent calcination treatment of the precursor to form hollow cavity. The favorable composition and unique hollow structure endow these Fe‐doped CoO NTs with remarkable activity toward OER. When used as the electrocatalyst for OER, the Fe‐doped CoO NTs show a small overpotential of 282 mV at the current density of 10 mA cm−2, a low Tafel slope of 78.26 mV dec−1, and a high turnover frequency of 0.0965 s−1 at the overpotential of 282 mV, which is superior to those of CoO NTs and solid CoO nanoparticles. Moreover, the Fe‐doped CoO NTs also exhibit excellent long‐term stability of 24 h at the current density of 10 mA cm−2.

Enhancement of the photocatalytic response of Cu-doped TiO2 nanotubes induced by the addition of strontium

The influence of adding strontium to Cu-doped TiO2 nanotubes on the photocatalytic performance of the resulting materials was herein studied considering changes in structural, textural, optical and morphological properties. Addition of strontium was performed in a 0.2–1.0 wt% range while an optimized fixed Cu loading of 0.5 wt% was used. TiO2 nanotubes were obtained using alkaline hydrothermal treatment of P25 followed by a calcination treatment at 400 °C. The resulting TiNT material was then impregnated with copper using an incipient wetness impregnation followed by a new calcination at 400 °C (0.5Cu-TiNT). Strontium was then added under similar impregnation-calcination conditions. The effect of adding various amounts onto 0.5Cu-TiNT was therefore deeply characterized using X-ray diffraction, N2 adsorption–desorption measurements, scanning electron microscopy coupled with energy-dispersive X-ray analysis, Raman, UV–vis diffuse reflectance, X-ray photoelectron, and photoluminescence spectroscopies as well as determining dielectric properties.Results clearly emphasize that up to a Sr loading of 0.8 wt%, the addition of Sr results in in situ formation of Sr-O-Ti entities on the surface of 0.5Cu-TiNT. Above this threshold loading, excess Sr loading leads to the formation of segregated SrO species. Finally, a direct correlation was observed here between the optimized formation of surface Sr-O-Ti entities and an enhanced photocatalytic response due to improved stabilization of photogenerated charges on 0.5Cu-TiNT resulting from the ferroelectric interference of neighboring SrTiO3 entities.

Cobalt Phthalocyanine Supported on Mesoporous CeO2 as an Active Molecular Catalyst for CO Oxidation.

Heterogenization of biomolecules by immobilizing on a metal oxide support could greatly enhance their catalytic activity and stability, but their interactions are generally weak. Herein, cobalt phthalocyanine (CoPc) molecules were firmly anchored on a Ce-based metal-organic framework (Ce-BTC) due to π-π stacking interaction between CoPc and aromatic frameworks of the BTC linker, which was followed by a calcination treatment to convert Ce-BTC to mesoporous CeO2 and realize a molecular-level dispersion of CoPc on the surface of CeO2. Various characterization results confirm the successful fabrication of molecular-based CoPc/CeO2 catalysts which exhibited good CO oxidation performance. Importantly, we found that the mixing manner of Ce-BTC and CoPc remarkably affects the physicochemical properties which then determined the catalytic performance of the resultant CoPc/CeO2 catalysts. In contrast, the direct physical mixing of CoPc and CeO2 led to poor performance toward CO oxidation, manifesting that the Ce-BTC-mediated CoPc loading strategy is promising for the heterogenization of catalytic biomolecules.

Rational design heterostructured bimetallic selenides for high capacity and durability sodium/potassium-ion storage

• The synergistic effects effectively improve the electrochemical performance. • DFT calculation was performed to unveil the interaction between CoSe 2 and Cu 2 Se. • The reaction mechanism was investigated via in-situ / ex-situ XRD and HRTEM. Transition metal selenides are regarded as a type of promising candidate anode material for sodium/potassium ion batteries owing to their high theoretical specific capacity. However, it is still a challenge to design and construct appropriate nanostructures to address the fatal issue of vast volume variation stemmed from repeated ion intercalation/deintercalation. Herein, simple solvothermal method combined with calcination treatment was applied to synthesis CoSe 2 -Cu 2 Se nanospheres encapsulated in nitrogen-doped carbon shells (CoSe 2 -Cu 2 Se@NC) as high-performance anode material for sodium/potassium ion batteries. The as obtained CoSe 2 -Cu 2 Se@NC electrode features unique heterogeneous structure, uniform carbon coating, large specific surface area and synergistic effects, which ultimately accelerate charge/electron transfer, restrain volume expansion, and thus improve electrochemical performance. Density functional theory results disclose the heterojunctions existed in the CoSe 2 -Cu 2 Se interface contribute to the prominent rate capability for the composite. As a result, CoSe 2 -Cu 2 Se@NC nanospheres displays good rate performance and improved durability in cycling for sodium/potassium ion batteries. In additional, the depth reaction mechanism of CoSe 2 -Cu 2 Se@NC were explored by in-situ and ex-situ XRD analyses.

Fluvial Sediments as SCMs: Characterization, Pozzolanic Performance, and Optimization of Equivalent Binder

This paper presents an assessment of recycling of thermally treated fluvial sediments as a supplementary cementitious material (SCM). Different calcination treatments were conducted with temperatures ranging between 450°C and 950°C. For each calcined sediment, a detailed characterization was carried out. Subsequently, blended cements containing 25% calcined sediments (CS) were prepared and tested, including portlandite consumption, hydration kinetics, and compressive strength development (41 and 52 MPa at 7 and 90 days, respectively). The results showed that blended cement based on CS at 750°C provided the most favorable hydration kinetics and the highest compressive strength. An optimization design of experiment was followed to maximize the substitution rate of CS. The resulting multivariable function suggests a replacement rate up to 20% to produce a blended cement equivalent to CEM II 52.5 N, and up to 30% to produce a cement equivalent to CEM II 42.5 N. The reported technoenvironmental findings corroborate the use of CS as SCMs and motivate future research on their effect on concrete properties.

Ultrasound assisted synthesis of heterostructured TiO2/ZnFe2O4 and TiO2/ZnFe1.98La0.02O4 systems as tunable photocatalysts for efficient organic pollutants removal

As a response to the everyday growing concern about wastewater treatment, some new mesoporous TiO 2 /ZnFe 2 O 4 and TiO 2 /ZnFe 1.98 La 0.02 O 4 catalysts were synthesized during this research. The ultrasound template-assisted sol-gel method was employed in the synthesis, using conventional calcination and microwave treatment for pore directing agent removal. The as-prepared samples were characterized from the structural, optical, morphological and textural points of view, confirming the presence of spinel ferrites and TiO 2 anatase crystals in the nanocomposites. The synthetized powders exhibit promising characteristics for their use in adsorption and light activated degradation of organic pollutants. The photodegradation experiments of model pollutant basic blue 9 (methylene blue) dye were performed at laboratory scale and the optimum experimental parameters were determined as 0.4 g/L catalyst and 30 mg/L initial dye concentration, under UV light irradiation, visible irradiation and natural sun light irradiation. The conventionally calcined lanthanum doped TiO 2 /ZnFe 1.98 La 0.02 O 4 system exhibited the highest efficiencies of 97%, 70% and 91% for dye removal from the solution, under UV light, visible light and natural sun light irradiation, respectively. Moreover, the catalytic activity was similar for up to four consecutive cycles. A lower yield of organic pollutant removal was observed in wastewater treatment plant (WWTP) effluent. The obtained results show that the newly synthesized catalysts are good candidates for the removal of water pollutants through adsorption and photocatalysis.

Calcination Condition of Dolomite‐Based Materials Influencing Static Dissolution in Synthetic Electric Arc Furnace Slag

The addition of basic additives in steelmaking processes is essential because these lead to slag adaptation and enable refining reactions. In calcination treatment, the process parameters temperature and dwell time influence the decomposition of dolomite as a magnesium‐containing lime substitute. It results in specific properties such as varying residual fractions of carbonates CaCO3·MgCO3 and porosity. The properties affect the dissolution kinetics, and the fast and complete dissolution is of interest. Hence, the static high‐temperature dissolution tests using dolomite‐based samples in diverse conditions (raw, modified, soft‐burnt, and hard‐burnt) are executed to determine the impact of the calcination state. The specimens are immersed in synthetic electric arc furnace slag, including 10 wt% Al2O3, 25 wt% SiO2, 25 wt% CaO, 8 wt% MnO, and 32 wt% FeO. The dolomite or dolime dissolves in the stagnant oxidic melt within the reaction time of 10 min at 1450 °C. The resulting chemistries of quenched slags, representing the current dissolution status, are examined by scanning electron microscopy using energy‐dispersive X‐ray spectroscopy analysis on metallographically prepared cross‐sections and via X‐ray fluorescence analysis of mechanically extracted slag fractions. The dissolution performance is characterized and compared for the different additive materials.

Red mud supported on reduced graphene oxide as photo-Fenton catalysts for organic contaminant degradation

In this study, the reduced graphene oxide (rGO) modified red mud (RM) composite was successfully prepared and used as the highly effective heterogeneous photo-Fenton catalyst for Rhodamine B (RhB) contaminant degradation. The acid leaching and calcination treatment reduced the impurities in RM, making α-Fe2O3 active for H2O2 decomposing. The rGO modification can not only inhibit the recombination of charge carriers but also accelerate the Fe3+/Fe2+ cycle during heterogenous Fenton process. Attributed to such advantages, 99.8% degradation of RhB within 20 min was achieved by the optimal RM-H/rGO composite. More importantly, the prepared RM-H/rGO showed excellent performance and high stability for various organic contaminants degradation at a wide pH range. This study not only demonstrates that rGO-modified RM can be used as an efficient, low-cost photo-Fenton catalyst for organic pollutants treatment, but also provides an effective approach for RM disposal.

Fabrication and Characterization of Nickel Oxide Nanofibers by Electrospinning Technique

Nickel Oxide nanofibers were successfully prepared by electrospinning with a precursor mixture of Ni acetate/polyvinylpyrrolidone (PVP), followed by calcination treatment of the electrospun composite nanofibers. The parameter of solution and effect of applied voltage to the morphology of nanofibers were studied. Both Ni acetate/PVP and NiO NFs, nanofibers were characterized by FESEM and XRD. The results found that the nanofibers form with smooth surface without beads and the calcination temperature was at 500°C to produce NiO nanofibers.

Activated Ni-based metal–organic framework catalyst with well-defined structure for electrosynthesis of hydrogen peroxide

Catalyst with well-defined active sites and highly ordered mesoporous structure is of significant importance for electrocatalytic synthesis of hydrogen peroxide (H2O2) by a two-electron oxygen reduction reaction (ORR). Herein, we present a Ni-based MOF two-electron ORR electrocatalyst derived from zeolitic imidazolate framework-8 (ZIF-8) for H2O2 production. The partial substitution of Zn in ZIF-8 with Ni (MOF Ni-250) affords a favorable two-electron ORR catalytic performance, where the elemental Ni serves as an excellent active site. In addition, the catalytic performance of the catalyst is further enhanced by calcination treatment of MOF Ni-250 under 300 ℃ (c-MOF Ni-250), which removes the crystal water and other small molecules within MOF, thus exposing the active sites and transfer channel of reaction species in catalyst layer without structure destruction. The optimized c-MOF Ni-250 exhibits an excellent H2O2 selectivity of 95% and a high H2O2 production rate of 0.51 mol·gcat.-1·h−1 at 0.37 V (vs. RHE) in 0.1 M KOH. The acitve sites of Ni atom is futher confirmed by using density functional theory (DFT) calculations. This finding demonstrates that the as-developed catalyst has a great potential in electrocatalytic synthesis of H2O2 in practical applications.

Effect of introducing zinc on the photoluminescence and stability of cesium lead halide perovskite materials

Metal halide perovskites are restricted by their stability and environmental detriment due to the participation of expensive and toxic reagents. We have selected a green dry mechanical grinding method to synthesize the perovskite materials, and with the introduction of Zn powder (CZ), most of the bulk CsPbBr3/Cs4PbBr6 phases (pure C) are converted to Cs2ZnBr4, which separates the remaining CsPbBr3 NCs to form heterostructures on the surface ZnO layer of Zn. The photoluminescence (PL) of the resultant CZ samples first increases and then decreases as the Zn dosage changes, and the PL intensity of the optimum sample with 10 mmol of Zn (CZ10) increases to about 8 times that of pure C. The largely enhanced PL of CZ10 is originated from the remaining CsPbBr3 NCs promoted by the weakened charge transfer from CsPbBr3 to Cs2ZnBr4 and the metallic Zn due to the formation of a quasi-type I heterostructure of Cs2ZnBr4/ZnO. After the calcination treatment at 700 ℃ (CZ10-C700), 80% of PL is maintained, but the photostability of CZ10-C700 is greatly enhanced compared with that of CZ10, and 99.3% of PL is kept after 150 h illumination, which is attributed to the encapsulation protection of CsPbBr3/Cs2ZnBr4 by the ZnO layer on Zn.

Shearing Sulfur Edges of VS2 Electrocatalyst Enhances its Nitrogen Reduction Performance.

Electrochemical N2 fixation requires effective electrocatalysts to expedite the nitrogen reduction reaction (NRR) kinetics and suppress the concomitant hydrogen evolution reaction (HER). Although transition metal sulfides have been deemed as efficient NRR electrocatalysts, it remains a great challenge to suppress the serious HER to achieve high Faradaic efficiency (FE). Herein, vanadium disulfide (VS2 ) is deliberately designed by partially shearing its sulfur (S) edges through a simple calcination treatment at 350 °C. The as-prepared VS2 -350 electrocatalyst exhibits a highest NH3 yield of 20.29µg h-1 mgcat-1 with a promising FE of 3.86%, which is significantly higher than the counterpart of untreated VS2 (VNH3 : 15.92µg h-1 mgcat-1 , FE: 1.69%). Experimental and computational results reveal that shearing the S edges can substantially inhibit the HER and expose more V atoms as active sites. Meanwhile, the mechanistic analysis shows that the N2 activation at V active sites follows an "acceptance-donation" mechanism, while the N2 conversion to NH3 follows a hybrid 2 pathway at the VS2 -350 electrocatalyst. This work provides a simple strategy of designing high-performance NRR electrocatalysts based on a deep understanding of the atomic sites dependent catalytical activity.

Chemistry and mineralogy of Zr- and Ti-rich minerals sourced from Cox’s Bazar beach placer deposits, Bangladesh: Implication of resources processing and evaluation

Zircon is always found in association with Ti-rich minerals; therefore, it is produced mainly as a co-product in the production of ilmenite and rutile from placer mining operations. In Cox’s Bazar beach sands, they contain at 2.8, 12.1 and 2.7 wt% (average) respectively in the heavies. In order to scrutinize mineralogical and geochemical variability among Zr- and Ti- rich minerals, XRF, XRD, SEM and EPMA were implemented. Petrogenesis manifests the nature of impurities in mineral concentrates where they included through cationic substitution during alteration and metamictization, whereas their coating and pore filling occurred by hydraulic action in fluvial process. The impurities of oxides, silicates and phosphates gangue mineral phases degrade the quality of zircon concentrate (ZrO2 + HfO2 = 63.73 wt%) in achieving premium grade. Although the process of hot acid leaching (HAL) upgrades the quality enhancing ZrO2 + HfO2 (69.10 wt%) content, yet to be eliminated Fe and U to reach premium grade. Thermal annealing and calcining treatment is suggested to fully recover the zircon prior to industrial use. Similar to zircon, ilmenite and rutile they both contain trace levels of gangue mineral phases. The content of TiO2 and Ti/(Ti + Fe) (48.1 wt% and 0.5 respectively) indicates unaltered ilmenite. Therefore, upgrading the unaltered low grade ilmenite concentrate to chlorination feedstock, ilmenite smelting and the synthetic rutile routes are suggested. In addition, the TiO2 (83.84 wt%) content in the bulk rutile concentrate shows as much as the high grade ilmenite display due to contaminants. Mentioning, two of the major impurities such as tin and zirconium occurred as mineral grain cassiterite and zircon and as substitutions for titanium (Ti ⇌ Sn, Zr) in crystal lattice. The way of acid leaching can be instrumental not only for upgrading rutile but also for extracting Sn and Zr as byproduct of Ti metal/ TiO2 pigment.

SYNTHESIS OF CERIA NANOPARTICLES: EFFECT OF ALCOHOL/WATER RATIO ON THE MORPHOLOGY AND CRYSTAL STRUCTURE

In this study, ceria nanoparticles were synthesized via one of the simplest methods, which is the precipitation method. The effects of three different ethanol/DI water ratios (i.e. 1:1; 1:4; 0:1) and post-heat treatments (i.e. drying only and drying + calcination) on the crystal structure and morphology of the ceria nanoparticles have been investigated. The characterization of the ceria nanoparticles was conducted using X-Ray Diffractometer (XRD) for the crystal structure and Transmission Electron Microscopy (TEM) for the morphology. From XRD analysis results, the comparison of the highest XRD intensity peaks (at 2θ = 28.6°) of the ceria nanoparticles samples showed that all the ceria nanoparticles samples with drying + calcination treatment were higher than the ones with drying treatment only. Additionally, the XRD peaks were analyzed using a well-known Scherrer’s equation to determine the average crystallite size of the ceria nanoparticles. It was found that the ceria nanoparticles sample prepared using the ethanol/DI water ratio of 1:1 (i.e. Ceria-C1) had the biggest average crystallite size (i.e. 14 nm). Nevertheless, the TEM analysis showed that Ceria-C1 showed better morphology and dispersion compared to other Ceria samples and also clearly exhibited sphere-like nanoparticles. This finding can be associated with the dispersion stability analysis, which showed that the suspension of Ceria-C1 shows a little bit better dispersion compared to other Ceria samples.

Catalytic activity of ethylbenzene with product selectivity by gold nanoparticles supported on zinc oxide.

The oxidation of ethylbenzene (EB) using tert-butyl hydroperoxide as the oxidizing agent was carried out in presence of gold nanoparticles (3 nm) supported on zinc oxide in acetonitrile solution. A higher selectivity towards acetophenone (ACP) as the major product, and a moderate selectivity towards other products such as 1-phenylethanol (PE), benzaldehyde (BZL), and benzoic acid (BzA) were observed using the prepared Au/ZnO nanocatalysts at 100 °C for 24 h. It is suggested the reaction produces an intermediate product, which is dimethylethyl-1-phenylethyl peroxide through a radical mechanism. A small amount of benzaldehyde was observed because benzaldehyde went autoxidation to form benzoic acid with the presence of oxidation agent of TBHP during reaction. The factors affecting the catalytic activity such as gold loading, calcination treatment at 300°C, type of solvent, reaction time, reaction temperature, oxidant to substrate molar ratio, catalyst weight, and solvent volume were studied. The gold nanoparticle catalyst synthesized by deposition precipitation method using urea was characterized by XRD, HRTEM, ATR-IR, XRF, and BET and offers a very selective reaction pathway for the oxidation of ethylbenzene.

Nitrogen and sulfur co-doped CeO2 nanorods for efficient photocatalytic VOCs degradation

Nitrogen and sulfur-co-doped ceria with a regular nanorod morphology was prepared by one-step calcination treatment. N and S dopants can generate new impurity level states and promote the photocatalytic performance of CeO2 for VOCs degradation.

Immobilised rGO/TiO2 Nanocomposite for Multi-Cycle Removal of Methylene Blue Dye from an Aqueous Medium

This work presents the immobilisation of titanium dioxide (TiO2) nanoparticles (NPs) and reduced graphene oxide (rGO)-TiO2 nanocomposite on glass sheets for photocatalytic degradation of methylene blue (MB) under different radiation sources such as ultraviolet and simulated solar radiation. The TiO2 NPs and rGO-TiO2 nanocomposite were synthesised through a simple hydrothermal method of titanium isopropoxide precursor followed by calcination treatment. Deposition of prepared photocatalysts was performed by spin-coating method. Additionally, ethylene glycol was mixed with the prepared TiO2 NPs and rGO-TiO2 nanocomposite to enhance film adhesion on the glass surface. The photocatalytic activity under ultraviolet and simulated solar irradiation was examined. Further, the influence of different water matrices (milli-Q, river, lake, and seawater) and reactive species (h+, •OH, and e−) on the photocatalytic efficiency of the immobilised rGO/TiO2 nanocomposite was careful assessed. MB dye photocatalytic degradation was found to increase with increasing irradiation time for both irradiation sources. The immobilisation of prepared photocatalysts is very convenient for environment applications, due to easy separation and reusability, and the investigated rGO/TiO2-coated glass sheets demonstrated high efficiency in removing MB dye from an aqueous medium during five consecutive cycles.

Hollow flower-like Cr2V4O13 hierarchical micro-nano architectures: Controlled self-assembly synthesis and the outstanding catalytic performances for ammoxidation of chlorotoluenes

The controlled synthesis of hierarchical micro-nano materials has attracted great interest due to their wide applications in catalysis and many other fields. In this paper, hollow flower-like Cr2V4O13 hierarchical micro-nano structures were successfully synthesized via a facile hydrothermal process and subsequent calcination treatment. The samples were characterized by XRD, TGA, FT-IR, SEM, TEM, XPS, TPR and N2 adsorption-desorption. SEM and TEM micrographs showed that the as-obtained Cr2V4O13 had a three-dimensional (3-D) hollow flower-like superstructure assembled by numerous nanoflakes with widths of 0.2 µm and thickness of about 30 nm. The micro-nano structured Cr2V4O13 exhibited high activity and selectivity in continuous ammoxidation of chlorotoluenes to the corresponding chlorobenzonitriles. To the best of our knowledge, this is the highest activity reported for selective ammoxidation of chlorotoluenes with Cr-V-O binary catalysts. The unique catalytic behavior of Cr2V4O13 was ascribed to the micro-nano hierarchical architecture and the increased active surface sites.

Bismuth-doped cobaltosic oxide as a noble-metal free electrocatalyst for the efficient methanol oxidation reaction

BackgroundMethanol electro-oxidation reactions (MOR) are utilized to provide electricity in direct methanol fuel cells (DMFC), which requires a reasonable design of catalysts to accelerate sluggish MOR. Herein, a series of cobalt oxides have been doped with a foreign oxophilic transition metal (Bi) by the sol-gel method and further calcination treatment. MethodsThe composition and structure of Bi0.13Co2.87O4-550 were characterized by the scanning electron microscopy (SEM), the powder X-ray diffraction (XRD), and X-ray photoelectron spectra (XPS). Evaluate the electrocatalytic performance of materials by cyclic voltammetry, chronoamperometry, and impedance spectroscopy. Significant findingsBy virtue of the tunable compositional and structural advantages, the optimized Bi0.13Co2.87O4-550 nanocomposite shows the excellent electrocatalytic activity, very high mass activity (808.5 mA mg−1), as well as remarkable durability to resist CO poisoning during methanol oxidation. The excellent electrocatalytic activity for MOR is attributed to the high specific surface area, abundant active sites and superior mass transportability. Furthermore, the oxidation of other alcohols including ethanol, ethylene glycol and glycerol are also realized by the electrocatalysis of Bi0.13Co2.87O4-550. This work provides a good idea for the design of non-precious metal electrocatalysts with the high performance.

Fabrication of Pd/In2O3 Nanocatalysts Derived from MIL-68(In) Loaded with Molecular Metalloporphyrin (TCPP(Pd)) Toward CO2 Hydrogenation to Methanol

Methanol synthesis from CO2 hydrogenation with H2 produced from renewable energy has emerged as a promising method for carbon neutrality. The supported Pd/In2O3 catalyst has attracted great attention due to its superior activity and methanol selectivity, but the formation of the In–Pd bimetallic phase upon over-reduction would lead to quick catalyst deactivation. In this work, we elucidate the reduction behavior of Pd/In2O3 catalysts by using TCPP(Pd)@MIL-68(In) as precursors. During catalyst fabrication, metalloporphyrins (viz., TCPP(Pd)) served as both a capping agent for the growth of MIL-68(In) and a shuttle for transporting the Pd2+, which enhanced the dispersion of Pd0 species on In2O3–x during the calcination and reduction treatments and prevented the formation of In–Pd bimetallic phase by over-reduction. With a low Pd loading of 0.53 wt %, the resultant Pd/In2O3 catalyst exhibited a maximum methanol space–time yield of 81.1 gMeOH h–1 gPd–1 with a CO2 conversion of 8.0% and a methanol selectivity of 81% over 50 h on stream (295 °C, 3.0 MPa, 19,200 mL gcat–1 h–1). In contrast, the comparative Pd/In2O3 catalyst prepared by the impregnation of PdCl2 in MIL-68(In) showed poor activity and stability due to the formation of InPd/In2O3–x surface structures. In addition, we found a strong connection between the reduced degree of In2O3 and the catalytic performance of the supported Pd/In2O3 catalysts by integrating catalyst characterization results with density functional theory (DFT) calculations. Interestingly, the surface In/O ratio detected by XPS can reflect information about both metal–support interaction and the amount of oxygen vacancy, which is highly related to the catalytic activity. The DFT calculation also shows that the Pd/In2O3 catalyst has excellent thermodynamic selectivity for the CH3OH product. This work provides an alternative synthetic strategy for Pd/In2O3 nanocatalysts and sheds light on the deactivation mechanism of the supported catalysts.