Subsequent Calcination Process Research Articles

X-ray spectromicroscopy of single NiO antiferromagnetic nanoparticles

The chemical and magnetic properties of NiO nanoparticles (NP) have been studied with single-particle sensitivity by means of synchrotron-based, polarization-dependent X-ray absorption spectroscopy using photoemission electron microscopy around the Ni L3,2 edges. Three samples of NP in a size range of 40-120 nm were synthesized by thermal decomposition and subsequent calcination processes. The analysis of the local X-ray absorption spectra of tens of individual NP indicates a strong dependence of their Ni oxidation state with the calcination protocol of each sample. Additional electron-microscopy-based images and spectra of a few individual NP as well as other standard macroscopic data are in very good agreement with these experimental findings. These results showcase the relevance of combining standard and advanced single-particle studies to gain further insight into the understanding and control of electronic and magnetic phenomena at the nanoscale.

Manipulating the d-band center of bimetallic molybdenum vanadate for high performance aqueous zinc-ion battery

Vanadium-based oxides have good application prospects in aqueous zinc ion batteries (AZIBs) due to their structures suitable for zinc ion extraction and intercalation. However, their poor conductivity limits their further development. The d-band center plays a key role in promoting adsorption of ions, which promotes the development of electrode materials. Here, a series of MoV2O8 compounds with oxygen defect (Od-MoV2O8) were synthesized by a simple hydrothermal process and a subsequent vacuum calcination process through strict control of the deoxidation time. Theoretical calculations reveal that the abundant oxygen vacancies in MoV2O8 effectively regulate the d-band center of the zinc ion adsorption site. This precise control of the d-band center enhances the zinc ion adsorption energy of MoV2O8, lowers the migration energy barrier for zinc ions, and ultimately significantly boosts zinc storage performance. The specific capacity is as high as 282.4 mAh/g after 100 cycles at 0.1 A/g, and it also shows excellent performance and outstanding cycle life. In addition, the maximum energy density of Od-MVO-0.5 (MoV2O8 sample deoxidized for 0.5 h) is 343.3 Wh kg−1. Importantly, the mechanism of Zn2+ storage in Od-MoV2O8 was revealed by the combination of in situ and ex situ characterization techniques.

Modulation of charge structure in Bi/Bi2O3-In2O3@C for efficient CO2 electroreduction to formate

Electrocatalytic CO2 reduction reaction (ECO2RR) to value-added chemicals is of significant importance to control CO2 emission and reach carbon neutrality. Herein, Bi/Bi2O3-In2O3@C electrocatalyst with nanosheet arrays is successfully fabricated by a facile solvothermal with subsequent calcination process. It is found that the electron structure of Bi/Bi2O3-In2O3@C can be adjusted by the synergistic effects of Bi-In hetero-diatoms, which can significantly enhance its inherent catalytic activity. As expected, it requires a maximum HCOOH faradaic efficiency (FEHCOOH) of 97.6 % at −1.1 V vs. Reversible Hydrogen Electrode (RHE), which further delivers over 90 % at a wide potential range of −0.8 to −1.4 V vs. RHE, and exhibits high stability of 90.1 % over 60-h long-term test. In-situ Raman analysis is performed to explore the mechanism of its excellent stability. Meanwhile, in-situ attenuated total reflection-Fourier-transform infrared (ATR-FTIR) analysis combined with theoretical calculations reveal that the hetero-bridging absorption of *OCHO and d-d orbital coupling effect can regulate d-band center of Bi/Bi2O3-In2O3@C and improve its density of states around Ef, moderating free energy of intermediates, thereby the improved formate production performance can be seen.

Controllable fabrication of cobalt molybdate nanofibers with oxygen vacancies induced by calcinable polymer for peroxymonosulfate activation towards water treatment

Cobalt-based oxides are efficient Fenton-like catalysts to activate peroxymonosulfate (PMS) towards polluted water treatment. However, the relatively low catalytic performance still hinders their promising practical application. Herein, we have demonstrated a distinct Fenton-like catalyst of oxygen vacancies-rich cobalt molybdate (CoMoO4) nanofibers induced by calcinable polymer (CoMoO4/CPAN), which are prepared through an electrospinning and subsequent hydrothermal and calcination process. Owing to the presence of oxygen vacancies to manipulate the electron-donation property, the production of reactive oxygen species (ROS) is promoted. Radical quenching and the electron paramagnetic resonance (EPR) experiments reveal that the generation of non-radical 1O2 is a primary pathway to contribute to the degradation performance of the catalyst. Resultingly, the obtained CoMoO4/CPAN catalyst presents a superior degradation property towards organic pollutants (e.g. rhodamine B, RhB) with a reaction rate constant of 0.671 min−1, significantly surpassing the bare CoMoO4 catalyst (0.138 min−1) and many other recently reported Fenton-like catalysts. Furthermore, the developed Fenton-like system shows a desirable degradation property in actual water bodies, displaying great potential for water treatment. Our study offers a new avenue to develop highly active Fenton-like catalysts for wastewater remediation.

Synthesis and characterization of aluminum hydroxide-reinforced silica-zirconia ceramic membrane for thermal protection applications

In the domain of personal thermal protection, there is a growing demand for lightweight and efficient ceramic thermal insulation materials. However, conventional ceramic membranes face challenges such as brittleness, structural collapse, and pulverization, hindering their practical application. To address this issue, aluminum hydroxide-enhanced silica-zirconia ceramic membranes (SZ@ANFMs) have been successfully fabricated using electrospinning followed by subsequent calcination processes, and their properties have been comprehensively evaluated. The results demonstrate that SZ@ANFMs exhibit outstanding high-temperature resistance under an alcohol lamp, along with an extremely low thermal conductivity (only 0.041 W/m·K), excellent tensile strength (2.3 MPa), and flexible characteristics. This makes them highly promising in the domain of personal thermal protection. The study builds upon existing research in lightweight and efficient thermal insulation materials, offering improvements and robust support for the further development of personal thermal protection technology.

Fabricating Ion Sieves by 3D Printing for Selective Lithium Adsorption from Brines

AbstractThis work presents the formation of a stable 3D monolith based on manganese oxide for the adsorption of lithium from brine. The precursor phase was prepared by microwave‐assisted hydrothermal synthesis and a subsequent calcination process to achieve the desired crystalline phase LiMn2O4. The monolith was formed using additive manufacturing, which allowed its size and shape to be controlled. Subsequently, this monolith was washed with a HCl solution to generate adsorption sites for lithium. The prepared materials were characterized by XRD, FTIR, TGA, N2 physisorption, and SEM‐EDS. Analysis confirmed that the 3D monolith retained its crystalline structure throughout the process. The kinetic characteristics of the adsorption process were evaluated using pseudo‐first and pseudo‐second order equations, as well as Freundlich and Langmuir equations, to describe thermodynamic equilibrium. Monoliths were able to capture lithium up to 13.84 mg/g and the Freundlich equation described the equilibrium (R2=0.9751), while the second‐order equation better described the kinetic behavior (R2=0.9130). Results showed that monoliths are selective towards lithium in the presence of competing cations. The stability of the materials was evaluated in adsorption‐desorption cycles, demonstrating a competitive reuse after five cycles. This research presents a promising new approach for developing efficient lithium extraction methods from brine.

Carbon nanotubes-encapsulated Co/Co7Fe3 nanocomposites: Achieving wideband electromagnetic wave absorption at ultrathin-thickness by regulating magnetic phase ratio

Nowadays, through various strategies such as composition regulation and structural design, the electromagnetic wave (EMW) attenuation ability of composites has been significantly improved. Nevertheless, at ultra-thin sample matching thicknesses, it is still a challenge for absorbing materials to possess high-intensity and wide bandwidth simultaneously. In this work, the cobalt/iron nitrilotriacetic acid chelates (Co/Fe-NAC) were fabricated by a one-step hydrothermal self-assembly strategy. Then, a series of carbon nanotubes-encapsulated Co/Co7Fe3 (Co/Co7Fe3@CNTs) nanocomposites were constructed by coating glucose hydrothermal carbon on Co/Fe-NAC precursors and subsequent calcination process. By controlling the Co/Fe ion content, the magnetic phase ratio in the product can be efficiently regulated to comprehensively optimize microwave absorption (MA) performance. The minimum reflection loss (RL) of the optimized sample is −42.6 dB at only 1.1 mm thickness, and the effective absorption bandwidth (EAB) reaches up to 10.1 GHz (7.9–18 GHz). Surprisingly, for all samples, the widest EAB can exceed 8.2 GHz at the ultra-thin thickness (thinner than 1.3 mm) and the strongest RL values are all below −30 dB (99.9 % EMW can be absorbed). Such excellent MA performance is attributed to the strong magnetic loss of highly dispersed magnetic nanoparticles, the strong dielectric properties of carbon nanotubes and shells, optimized impedance matching, as well as the synergistic effect of multi-dimensional heterogeneous components and structures. Moreover, the high-frequency structure simulator (HFSS) was used to further analyze the multi-polarization behaviors and heterogeneous magnetic coupling effect. This work may provide a new direction to the fabrication of efficient and ultra-thin absorbers, and Co/Co7Fe3@CNTs nanocomposites may become a promising candidate for practical application in the MA field.

Enhanced Performance of Complementary Electrochromic Device with Hierarchical‐Porous NiO x Decorated ITO Glasses as the Transparent Conductive Electrodes

To pursuit advancing electrochromic technology, the preparation of a novel hierarchical‐porous NiOx‐decorated ITO transparent conductive electrode was developed through the vapor‐assisted conversion and subsequent calcination processes. The modified transparent electrode exhibited advantages in the electrodeposition of conductive polymer films, which significantly enhanced electrochromic cycling stability. Moreover, the complementary electrochromic device based on NiOx‐decorated ITO transparent electrode was fabricated, demonstrating rapid response time (1.75 s for coloration and 0.87 s for bleaching), high optical contrast (53.4%), and remarkable cycling stability (90% optical contrast retention over 2000 cycles). This finding holds prominent potential for applications in related fields.

Glucose-Assisted Synthesis of Porous, Urchin-like Co3O4 Hierarchical Structures for Low-Concentration Hydrogen Sensing Materials.

The Co3O4 is a typical p-type metal oxide semiconductor (MOS) that attracted great attention for hydrogen detection. In this work, porous, urchin-like Co3O4 was synthesized using a hydrothermal method with the assistance of glucose and a subsequent calcination process. Urchin-like Co3O4 has a large specific surface area of 81.4 m2/g. The response value of urchin-like Co3O4 to 200 ppm hydrogen at 200 °C is 36.5 (Rg/Ra), while the low-detection limit is as low as 100 ppb. The obtained Co3O4 also exhibited good reproducibility, long-term stability, and selectivity towards various gases (e.g., ammonia, hydrogen, carbon monoxide, and methane). Porous, urchin-like Co3O4 is expected to become a potential candidate for low-concentration hydrogen-sensing materials with the above advantages.

TiO2/Multi-walled carbon nanotube electrospun nanofibers mats for enhanced Cr(VI) photoreduction

Industrial processes, including metal plating and paint production, generate substantial wastewater with hexavalent chromium (Cr(VI)), necessitating the development of efficient photocatalysts for its reduction. In this study, we fabricated curly hybrid nanofiber composites (TiO2/Multi-walled carbon nanotube (MWCNT)) with varying MWCNT contents (0.1, 0.3, 0.5, 0.7, and 1.0 w/w) via electrospinning and subsequent calcination process for Cr(VI) photoreduction efficiency. Our experimental results indicated an initial rise in specific surface areas and micropore volumes with increasing the MWCNT content up to TiO2/MWCNT-7, followed by a decrease, attributed to the development of a curly structure with the introduction of MWCNTs. This improved TiO2 dispersion, reduced the band gap, and densified the composites, enhancing mass transfer properties and visible light utilization. As a result, TiO2/MWCNT-7 exhibited a significant redshift in wavelength along with a 2.93 eV band gap, resulting in 97.5% Cr(VI) photoreduction efficiency within 120 min and sustained 92% efficiency over 6 cycles. This study offers insights for catalyst design and optimization in Cr(VI) photoreduction for water treatment applications.

Effectiveness of green-synthesized nickel-doped calcium ferrite nanoparticles in the X-ray/gamma radiation shielding applications

Nanoparticles comprising calcium ferrite doped with Nickel within a concentration range of 10 to 50 mol% were successfully produced using a solution combustion technique, employing neem leaf extract as a reducing agent. The subsequent calcination process at 500 °C validated the formation of orthorhombic calcium ferrite, featuring distinct Bragg reflections indicative of Nickel doping. An analysis via scanning electron microscopy (SEM) affirmed the presence of irregularly shaped nanoparticles with pores and voids within their structure. The optical energy band gap, determined through Wood and Tauc’s relation, ranged from 2.89 to 2.97 eV. Notably, an increase in Nickel substitution was found to correlate with an increase in the energy band gap and a reduction in crystallite size. The research extensively evaluated the nanoparticles’ efficacy in radiation protection, encompassing parameters such as mass attenuation coefficient, mean free path, half-value layer, and effective atomic number. The mass attenuation coefficient is found to be 0.05353 cm2g−1 for 40 mol% at 1332 KeV. EABF is found to be large for 40 mol% at 0.89 MeV energy. Likewise, 50 mol% has a high Neutron absorption cross section (σab) which is 1.5(barn). Also, the bremsstrahlung dose rate is found to be 1.35 (R/h)*103, at 1.511 MeV.Additionally, the study comprehensively explored variations in the energy-absorbing buildup factor across diverse energy ranges, taking into account the Nickel concentration within the calcium ferrite nanoparticles. This aspect holds significant importance in the field of radiation dosimetry, particularly in applications related to neutron shielding and bremsstrahlung radiation.

Electrospun Mo2C-embedded carbon nanofibers: A promising material for supercapacitors with enhanced electrochemical performance

Recently there has been a growing fascination with two-dimensional (2D) materials, driven by their remarkable and distinctive characteristics. This paper introduces a straightforward, efficient, and affordable approach for producing Mo2C@CNF nanocomposite electrodes by using the Electrospinning (E-Spun) technique and subsequent calcination process. The Mo2C@CNF-1 and Mo2C@CNF-2 are E-spun, iodized, and notably Mo2C@CNF-2 is carried out by the ageing process. The purpose of the iodization and ageing process before carbonization is to create a stronger C=C backbone and to reduce carbon loss during the formation of carbon nanofiber. The physical properties of the sample were characterized using XRD, HRSEM, EDAX, HRTEM, XPS, and BET. Further, their electrochemical performance is comparatively studied for supercapacitor applications in three-electrode setups. The Mo2C@CNF-2 exhibits a high specific capacitance of 873 F g−1 with a coulombic efficiency of 88.4 % at 1 A g-1 current density. Further studies on the electrochemical performance of symmetric Mo2C@CNF-2 devices show 126 F g−1 capacitance indicating its good electrochemical performance at 0.1 A g−1. Furthermore, the charge storage kinetics studied for the Mo2C@CNF-2 device, shed light on the insertion/de-insertion process of electrolytic ions being responsible for its excellent performance.

Highly (002)-oriented ZnO in ZnO-N-C microflakes coating layer for stable zinc anode in zinc-air batteries

Rechargeable alkaline zinc–air batteries (ZABs) are widely used in small electronic devices with high theoretical energy density, low cost, and environmentally friendly. However, Zn anode will emerge dendrite growth and corrosion problems during cycling and seriously affect the cycle life of the batteries. Thereby, a new ZnO-N-C microflake was synthesized as a protection layer for Zn anode by hydrothermal methods and subsequent calcination processes in this work. The ZnO with more preferred crystal plane (002) in the ZnO-N-C-600 microflakes can provide uniform charge distribution to induce the uniform deposition of Zn2+. And the strong interaction among each component in the ZnO-N-C can accelerate the electron transport to inhibit the violent growth of dendrites and further improve reversibility of Zn2+ plating/stripping. The Zn@ZnO-N-C-600 assembled symmetric battery achieves a stable 800 h cycling with a low polarization voltage (70 mV) at 0.5 mA cm−2, while the bare zinc symmetric battery has a cycle life of less than 170 h. Zn@ZnO-N-C -600 used as anode in alkaline zinc–air batteries shows comparable electrochemical performance. This work provides a broad application prospect for the development of a stable Zn anode for rechargeable zinc–air batteries.

A novel “On-Off” colorimetric sensor for ascorbic acid and hydrogen peroxide based on peroxidase activity of CeO2/Co3O4 hollow nanocubes

The development of artificial nanostructured enzymes has garnered significant interest in the field of nanobiotechnology due to the distinct advantages. In this work, CeO2/Co3O4 hollow nanocubes (named as CeO2/Co3O4 HNs) with exceptional peroxidase-like activity have been prepared employing ion exchange and subsequent calcination process. In the presence of hydrogen peroxide (H2O2), the CeO2/Co3O4 HNs display high peroxidase-like activity, catalyzing the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) and resulting in a color change from transparent to blue. The oxidized TMB (ox-TMB) is subsequently reduced to TMB due to the reducibility of ascorbic acid (AA), restoring the original color of solution. Consequently, a straightforward and efficient "On-Off" colorimetric sensor has been established for the accurate detection of H2O2 and AA, with detection limits (LOD) of 3.56 and 0.179 μM, respectively. In summary, the prepared colorimetric sensor offers numerous advantages, including ease of operation, cost-effectiveness, rapid response, and effective visual monitoring, which holds substantial promise for applications in detection of hydrogen peroxide and ascorbic acid.

Hydrothermal synthesis of ZnGa2O4 nanophosphors with high internal quantum efficiency for near-infrared pc-LEDs.

NIR luminescent materials have garnered widespread attention because of their exceptional properties, with high tissue penetration, low absorption and high signal-to-noise ratio in the field of optical imaging. However, producing nanophosphors with high quantum yields of emitting infrared light with wavelengths above 1000 nm remains a significant challenge. Here, we prepared a nanoscale ZnGa2O4:xCr3+,yNi2+ phosphor with good luminescence performance in near-infrared emission, which was synthesized via a hydrothermal method and subsequent calcination process. By co-doping with Cr3+ and Ni2+, the ZnGa2O4 phosphor shows a strong broadband emission of 1100-1600 nm in the second near-infrared (NIR-II) region, owing to the energy transfer from Cr3+ to Ni2+ with an efficiency up to 90%. Meanwhile, a near-infrared phosphor-conversion LED (NIR pc-LED) device is fabricated based on the ZnGa2O4:0.8%Cr3+,0.4%Ni2+ nanophosphor, which has under 100 mA input current, an output power of 23.99 mW, and a photoelectric conversion efficiency of 7.53%, and can be effectively applied in imaging and non-destructive testing. Additionally, the intensity ratio of INi/ICr of ZnGa2O4:0.8% Cr3+,0.4%Ni2+ with its high sensitivity value of 4.21% K-1 at 453 K under 410 nm excitation, indicates its potential for thermometry application.

Facial Construction of Hydroxyl Functional Modified Ultrafine BiPO4 with Variation of Dipole Moment Induced by –OH Group

The hydroxyl groups generated by hydrolysis are grafted onto the surface of BiPO4, and a stable surface hydroxylation structure is formed during the subsequent calcination process. This would facilitate the formation of a new hydroxyl functional structure on the surface of the parent photocatalyst without damaging its intrinsic structure. Synchronous illumination X‐Ray photoelectron spectroscopy shows that the hydroxyl functional ultrafine BiPO4 can realize the conversion of defective oxygen to lattice oxygen, which is more conducive in improving the photocatalytic efficiency. The process of filling hydroxyl oxygen vacancies and forming a stable structure is explored using in‐ situ infrared spectroscopy. The induced dipole moment promotes the separation of photogenerated electron–hole pairs, which is beneficial for the enhancement of photocatalytic activity. The dipole moment of the hydroxyl functional‐modified ultrafine BiPO4 is −1.409 D compared to −1.385 D for ordinary BiPO4. The results of this study indicate that hydroxyl functional structure and reduced sample granularity are effective strategies to improve the photocatalytic performance of BiPO4.

MIL-101-derived porous WO3/FeWO4 hierarchical structures with efficient heterojunction interfaces for excellent room temperature n-butanol-sensing performance

This study originally reports the in-situ construction of porous WO3/FeWO4 ribbon-like hierarchical composites with unique and intense heterojunction interface behavior and the enhanced adsorption and carrier transport capability for effectively detecting n-butanol at room temperature. The introduction of different adding amounts of MIL-101 plays the key role of the morphological evolution of WO3-based microstructures with the well-distributed nanoparticles in situ growth on the surface by a facile electrospinning and subsequent calcination process. Compared with pristine WO3, a sharp and useful reduction of the optimal operating temperature from 220 to 25 °C can be observed as the Fe component increasing, mainly owing to the inverted p-type gas sensitive response caused by the controllable variable of FeWO4 phase in the multiple effective WO3-FeWO4 heterojunctions. The optimal WO3/FeWO4 composites can display the highest response of 12.3 and a relatively short response/recovery times of 110/140 s to 100 ppm n-butanol at 25 °C, together with the superior gas selectivity, repeatability, humidity and long-term stability. Density functional theory (DFT) simulation is employed for verifying the significant adsorption interaction and charge transfer between n-butanol molecule and WO3/FeWO4. Regular distribution of WO3-FeWO4 heterojunction interfaces can not only determine the collaborative modulation of electronic structures, but also provide the efficient surface/interface transport mechanism for MIL-101 induced one-dimensional (1D) hierarchical ribbons. Actually, the integrated gas-sensitive components based on WO3/FeWO4 composites exhibit the rapid response characteristic under room temperature condition and provide a friendly strategy of optimizing the practical detection of ppm-level n-butanol for other inorganic heterogeneous sensors.

Lotus-root-like multichannel nanotubes of IrO2–ZnO for electrocatalysis of pH-universal oxygen evolution reaction: A simple strategy to control the structure and crystallinity

A series of IrO2-ZnO composite oxide nanomaterials (IrO2-ZnO-x) were synthesized by electrospinning and subsequent calcination process using an electrospinning solution composed of Ir/Zn metal precursors and blended polymers of PVP/PVDF at different mixing ratios (PVDF wt% out of total polymer is denoted as x = 0, 17, 33, 50, 100). The fine structure and crystallinity of the produced IrO2-ZnO-x materials were tuned simply depending on the polymer mixing ratio: As PVDF content increased in a polymer blend, IrO2-ZnO-x (x = 0, 17, 33, 50) changed the structure from wire-in-tubes to nanofibers and then to lotus-root-like multichannel nanotubes with a greater degree of amorphization via better alloying between Ir and Zn elements. IrO2-ZnO-33, exhibiting a lotus-root-like multichannel nanotubular structure with very porous surface morphology and low crystallinity, showed the best OER activity and long-term durable stability for 24 h in a wide range of pH solutions among a series of IrO2-ZnO-x, outperforming commercial Ir/C and a counterpart containing only Ir element. IrO2-ZnO-33 synthesized with an optimal polymer-blending ratio boosted up the electrocatalytic activity toward OER, which was ascribed to (1) enlarged surface area from its unique structure, (2) increased defects along with the greater amount of oxygen vacancies in the amorphous phase, and (3) the synergistic effect between Ir and Zn. This study presents a straightforward strategy to control the structure and crystallinity of nanocatalysts using a blend of properly selected two different polymers.

Exploring the photo-catalytic degradation of methyl orange dye using Strontium doped Bismuth oxide nanoparticles

Low dimensional metal oxide Nps have garnered significant attention due to their distinctive characteristics and diverse application domains. This investigation can provide further elucidation regarding the synthesis of Strontium doped-Bi2O3 efficacious photocatalysts operating under visible light, thereby potentially addressing environmental quandaries. The photoactivity of Strontium doped-Bi2O3 Nps exhibits a significantly greater magnitude when compared to that of Bi2O3 nanoparticles lacking Strontium doping. The hydrothermal method shall be employed for the synthesis of Strontium-doped Bismuth oxide in the course of preparation. A solution of NH4OH will be introduced to Bismuth nitrate and Strontium chloride. The resulting mixtures shall be subjected to vigorous stirring for a duration of 1 hour, after which they will be transferred into 100 mL autoclaves made of stainless steel and equipped with Teflon liners. These autoclaves shall then be heated to a temperature of 180 °C for a period of 6 h. The prepared samples shall subsequently undergo collection and undergo multiple washes utilising de-ionized water. In order to synthesise Strontium doped-Bi2O3 is imperative to subject the resulting compound to a subsequent calcination process at a temperature of 450° C. Infra-Red spectroscopy (FT-IR), UV-Visible, scanning electron microscopy (SEM), X-ray diffraction (XRD), techniques shall be employed for the investigation of the crystalline structures and morphologies of the powder. The resultant specimen shall subsequently serve as a catalyst for the photolytic degradation of organic dye methyl orange under diverse illumination circumstances. UV-Visible spectroscopy shall subsequently be employed to monitor the extent of photocatalytic efficacy.

One-Pot Synthesis of Ultra-Small Pt Nanoparticles-Loaded Nitrogen-Doped Mesoporous Carbon Nanotube for Efficient Catalytic Reaction.

In this study, Pt nanoparticles-loaded nitrogen-doped mesoporous carbon nanotube (Pt/NMCT) was successfully synthesized through a polydopamine-mediated "one-pot" co-deposition strategy. The Pt source was introduced during the co-deposition of polydopamine and silica on the surface of SiO2 nanowire (SiO2 NW), and Pt atoms were fixed in the skeleton by the chelation of polydopamine. Thus, in the subsequent calcination process in nitrogen atmosphere, the growth and agglomeration of Pt nanoparticles were effectively restricted, achieving the in situ loading of uniformly dispersed, ultra-small (~2 nm) Pt nanoparticles. The method is mild, convenient, and does not require additional surfactants, reducing agents, or stabilizers. At the same time, the use of the dual silica templates (SiO2 NW and the co-deposited silica nanoclusters) brought about a hierarchical pore structure with a high specific surface area (620 m2 g-1) and a large pore volume (1.46 cm3 g-1). The loading process of Pt was studied by analyzing the electron microscope and X-ray photoelectron spectroscopy of the intermediate products. The catalytic performance of Pt/NMCT was investigated in the reduction of 4-nitrophenol. The Pt/NMCT with a hierarchical pore structure had an apparent reaction rate constant of 0.184 min-1, significantly higher than that of the sample, without the removal of the silica templates to generate the hierarchical porosity (0.017 min-1). This work provides an outstanding contribution to the design of supported noble metal catalysts and also highlights the importance of the hierarchical pore structure for catalytic activity.