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Halide perovskite materials, especially lead-based perovskites, have been widely used for optoelectronic and catalytic applications. However, the high toxicity of the lead element is a major concern that directs the research work toward lead-free halide perovskites, which could utilize bismuth as a promising candidate. Until now, the replacement of lead by bismuth in perovskites has been well studied by designing bismuth-based halide perovskite (BHP) nanomaterials with versatile physical-chemical properties, which are emerging in various application fields, especially heterogeneous photocatalysis. In this mini-review, we present a brief overview of recent progress in BHP nanomaterials for photocatalysis under visible light. The synthesis and physical-chemical properties of BHP nanomaterials have been comprehensively summarized, including zero-dimensional, two-dimensional nanostructures and hetero-architectures. Later, we introduce the photocatalytic applications of these novel BHP nanomaterials with visible-light response, improved charge separation/transport and unique catalytic sites. Due to advanced nano-morphologies, a well-designed electronic structure and an engineered surface chemical micro-environment, BHP nanomaterials demonstrate enhanced photocatalytic performance for hydrogen generation, CO2 reduction, organic synthesis and pollutant removal. Finally, the challenges and future research directions of BHP nanomaterials for photocatalysis are discussed.

Herein, we present a novel bottom-up preparation route for heptazine-based polymers (melon), also known as graphitic carbon nitride. The growth characteristics of isolated 1D melon strings in microporous templates are presented and studied in detail. Removal of the microporous silicate template via etching is accompanied by the self-assembly of a 1D melon to stacked 3D structures. The advantages and limitations of the bottom-up approach are shown by using microporous templates with different pore sizes (ETS-10, ZSM-5, and zeolite Y). In accordance with the molecular size of the heptazine units (0.67 nm), a 1D melon can be deposited in ETS-10 with a pore width of about 0.78 nm, whereas its formation in the smaller 0.47 nm pores of ZSM-5 is sterically impeded. The self-assembly of isolated 1D melon to stacked 3D structures offers a novel experimental perspective to the controversial debate on the polymerization degree in 2D sheets of graphitic carbon nitride as micropore sizes below 1 nm confine the condensation degree of heptazine to isolated 1D strands at a molecular level. The growth characteristics and structural features were investigated by X-ray diffraction, N2 physisorption, scanning transmission electron microscopy/energy-dispersive X-ray analysis, 13C CP-NMR spectroscopy, and attenuated total reflection–infrared spectroscopy., Isolated 1D melon strands grow in microporous silicate templates. Removal of the silicate template via etching goes along with the self-assembly of the 1D melon to stacked graphitic carbon nitride. The self-assembly of an isolated 1D melon offers a novel experimental perspective to the controversial debate on the polymerization of graphitic carbon nitride as pore sizes below 1 nm confine the condensation degree of heptazine to isolated 1D strands at a molecular level.

Trichloroethylene (TCE) is one of the most abundant persistent organic pollutant in subsurface environment. TCE can be reduced electrochemically, but the extremely negative applied potential limits the application of this technology. Manganese phthalocyanine (MnPc) catalyst was used for the electrochemical reductive dechlorination of TCE. The results show that MnPc can be reduced by electrons attachment at −-0.21 V, −-1.22 V and −-1.77 V, respectively. With the decrease of applied potential from −-0.3 V to −-1.8 V, the transformation from TCE to dichloroethylene (DCE) efficiency increased from 19.9% to 41.8% after 5 hours of reaction. Although the electron transfer ability was enhanced with applied potential decreasing, the intensive HER caused the electron selectivity decreased when MnPc attached more electrons. MnPc catalyze the electrochemical reduction of TCE, which has potential application on the remediation of TCE-contaminated groundwater.

Photocatalysis is a promising yet challenging approach for the selective oxidation of hydrocarbons to valuable oxygenated chemicals with O

Chemistry - a European journal 27(45), 11600 - 11608 (2021). doi:10.1002/chem.202101117, Amorphous Ti$_x$O$_y$ with high surface area has attracted significant interest as photocatalyst with higher activity in ultraviolet (UV) light-induced water splitting applications compared to commercial nanocrystalline TiO$_2$. Under photocatalytic operation conditions, the structure of the molecular titanium alkoxide precursor rearranges upon hydrolysis and leads to higher connectivity of the structure-building units. Structurally ordered domains with sizes smaller than 7 Å form larger aggregates. The experimental scattering data can be explained best with a structure model consisting of an anatase-like core and a distorted shell. Upon exposure to UV light, the white Ti$_x$O$_y$ suspension turns dark corresponding to the reduction of Ti$^{4+}$ to Ti$^{3+}$ as confirmed by electron energy loss spectroscopy (EELS). Heat-induced crystallisation was followed by in situ temperature-dependent total scattering experiments. First, ordering in the Ti−O environment takes place upon to 350 °C. Above this temperature, the distorted anatase core starts to grow but the structure obtained at 400 °C is still not fully ordered., Published by Wiley-VCH, Weinheim

Although swarming motility and biofilms are opposed collective behaviors, both contribute to bacterial survival and host colonization. Pseudovibrio bacteria have attracted attention because they are part of the microbiome of healthy marine sponges. Two-thirds of Pseudovibrio genomes contain a member of a nonribosomal peptide synthetase-polyketide synthase gene cluster family, which is also found sporadically in Pseudomonas pathogens of insects and plants. After developing reverse genetics for Pseudovibrio, we isolated heptapeptides with an ureido linkage and related nonadepsipeptides we termed pseudovibriamides A and B, respectively. A combination of genetics and imaging mass spectrometry experiments showed heptapetides were excreted, promoting motility and reducing biofilm formation. In contrast to lipopeptides widely known to affect motility/biofilms, pseudovibriamides are not surfactants. Our results expand current knowledge on metabolites mediating bacterial collective behavior.

The groundwater environment often undergoes the transition from anoxic to oxic due to natural processes or human activities, but the influence of this transition on the fate of groundwater contaminates are not entirely understood. In this work, the degradation of tribromophenol (TBP) in the presence of environmentally relevant iron (oxyhydr)oxides (green rust, GR) and trace metal ions Cu(II) under anoxic/oxic-alternating conditions was investigated. Under anoxic conditions, GR-Cu(II) reduced TBP to 4-BP completely within 7 h while GR only had an adsorption effect on TBP. Under oxic conditions, GR-Cu(II) could generate •OH via dioxygen activation, which resulted in the oxidative transformation of TBP. Sixty-five percentage of TBP mineralization was achieved via a sequential reduction-oxidation process, which was not achieved through single reduction or oxidation process. The produced Cu(I) in GR-Cu(II) enhanced not only the reductive dehalogenation under anoxic conditions, but also the O

Owing to the easy over-oxidation, it is a promising yet challenging task to explore renewable carbon resources to control the sunlight-driven selective catalytic oxidation of biomass-derived 5-hydroxymethylfurfural (HMF), producing important chemical feedstocks, namely, less-oxidized 2,5-diformylfuran (DFF) and 5-hydroxymethyl-2-furancarboxylic acid (HMFCA). Herein, we have developed a photocatalyst by anchoring a Ru complex on CdS quantum dots, which achieves selective oxidation of HMF toward DFF or HMFCA with high conversion (81 %) and selectivity (90 %), based on the controllable generation of two oxygen radicals under different atmospheres. Such selective conversion can also work well outside the laboratory by using natural sunlight. In particular, the selective production of HMFCA through photocatalytic HMF oxidation is achieved for the first time. More importantly, our photocatalyst is applicable for the selective oxidation of other compounds with hydroxyl and aldehyde groups.

Reductive dechlorination of chlorinated organic pollutants (COPs) by Fe(II) occurs in natural environments and engineered systems. Fe(II) ions undergo hydroxylation in aqueous solutions to form Ferrous Hydroxyl Complex (FHC), which plays an essential role in Fe(II)-mediated reductive dechlorination. However, how hydroxyl groups of FHC bridge the electron transfer from Fe(II) to COPs is still not fully understood. This work shows that the rate of reductive dechlorination of carbon tetrachloride (CT) by FHC increased with increasing OH

Direct selective oxidation of hydrocarbons to oxygenates by O2 is challenging. Catalysts are limited by the low activity and narrow application scope, and the main focus is on active C−H bonds at benzylic positions. In this work, stable, lead‐free, Cs3Bi2Br9 halide perovskites are integrated within the pore channels of mesoporous SBA‐15 silica and demonstrate their photocatalytic potentials for C−H bond activation. The composite photocatalysts can effectively oxidize hydrocarbons (C5 to C16 including aromatic and aliphatic alkanes) with a conversion rate up to 32900 μmol gcat −1 h−1 and excellent selectivity (>99 %) towards aldehydes and ketones under visible‐light irradiation. Isotopic labeling, in situ spectroscopic studies, and DFT calculations reveal that well‐dispersed small perovskite nanoparticles (2–5 nm) possess enhanced electron–hole separation and a close contact with hydrocarbons that facilitates C(sp3)−H bond activation by photoinduced charges., Better with bismuth: A range of mesoporous‐silica‐supported small bismuth halide perovskite nanoparticles were prepared. They were found to be very promising photocatalysts for selective aromatic and aliphatic C−H bond activation under visible‐light illumination.

Solar-driven production of renewable energy (e.g., H2) has been investigated for decades. To date, the applications are limited by low efficiency due to rapid charge recombination (both radiative and nonradiative modes) and slow reaction rates. Tremendous efforts have been focused on reducing the radiative recombination and enhancing the interfacial charge transfer by engineering the geometric and electronic structure of the photocatalysts. However, fine-tuning of nonradiative recombination processes and optimization of target reaction paths still lack effective control. Here we show that minimizing the nonradiative relaxation and the adsorption energy of photogenerated surface-adsorbed hydrogen atoms are essential to achieve a longer lifetime of the charge carriers and a faster reaction rate, respectively. Such control results in a 16-fold enhancement in photocatalytic H2 evolution and a 15-fold increase in photocurrent of the crystalline g-C3N4 compared to that of the amorphous g-C3N4.

Herein, an innovative approach was developed by using stable, lead-free halide perovskite for solar-driven organic synthesis. The ring-opening reaction of epoxides was chosen as a model system for the synthesis of value-added β-alkoxy alcohols, which require energy-intensive process conditions and corrosive, strong acids for conventional synthesis. The developed concept included the in situ preparation of Cs3 Bi2 Br9 and its simultaneous application as photocatalyst for epoxide alcoholysis under visible-light irradiation in air at 293 K, with exceptional high activity and selectivity ≥86 % for β-alkoxy alcohols and thia-compounds. The Cs3 Bi2 Br9 photocatalyst exhibited good stability and recyclability. In contrast, the lead-based perovskite showed a conversion rate of only 1 %. The origin of the unexpected catalytic behavior was attributed to the combination of the photocatalytic process and the presence of suitable Lewis-acidic centers on the surface of the bismuth halide perovskite photocatalyst.

Nanoscale 13(1), 150 - 162 (2021). doi:10.1039/D0NR07871A, The exact formation mechanism of tantalum oxides (and in general, metal/mixed metal oxides) from alkoxide precursors is still not fully understood, particularly when forming cluster-like or amorphous materials. The structural evolution of Ta-based oxides was studied in detail using X-ray total scattering experiments along with subsequent pair distribution function (PDF) analyses. Starting from a tantalum alkoxide precursor (Ta2(OEt)10), the formation of hydrolysed TaxOyHz clusters in highly diluted aqueous solution was analysed. From the PDF data, the connectivity and arrangement of TaxOy octahedra in the cluster could be deduced as well as the approximate size of the clusters (, Published by RSC Publ., Cambridge

Collective behavior is a common feature of life. Although swarming motility and biofilms are opposed collective behaviors, both contribute to bacterial survival and host colonization. We have identified a link between motility/biofilms and a nonribosomal peptide synthetase-polyketide synthase gene cluster family (ppp) conserved in Pseudovibrio and Pseudomonas Proteobacteria known to interact with diverse eukaryotes. After developing reverse genetics for Pseudovibrio, we discovered two pseudovibriamide families, heptapeptides with a reversal in chain polarity via an ureido linkage 1-6 and related nonadepsipeptides 7-12. Imaging mass spectrometry showed that 1 was excreted whereas 7 was colony-associated. Deletion of pppA abolished production of 1-12 leading to reduced motility and increased biofilm production. pppD mutants that produced only 1-6 showed motility comparable to the wild-type and reduced biofilm formation, indicating that the excreted heptapeptides play a role in promoting motility. In contrast to lipopeptides widely known to affect swarming and biofilms, pseudovibriamides are not surfactants. Our results expand current knowledge on metabolites mediating bacterial collective behavior. Moreover, the establishment of reverse genetics will enable future exploration of the ecological and biotechnological potential of Pseudovibrio bacteria which have been proposed to contribute to marine sponge health.SignificanceBacteria contribute to health and disease of plants and animals. Specialized metabolites produced by bacteria are important in mediating their behavior and the colonization of their hosts. We have identified a conserved gene cluster family in Pseudovibrio and Pseudomonas bacteria known to colonize marine animals and terrestrial plants, respectively. Using Pseudovibrio as a model, we show the encoded metabolites, which we termed pseudovibriamides, promote motility and decrease biofilms. In contrast to lipopeptides widely known to affect motility/biofilms, pseudovibriamides are not surfactants, but instead are linear peptides with a reversal in chain polarity. The discovery of pseudovibriamides expands current knowledge of bacteria collective behavior. The establishment of reverse genetics will enable exploration of the ecological and biotechnological potential of Pseudovibrio bacteria.ClassificationBiological Sciences, Microbiology

The concept of being able to urinate in a cup and screen for colorectal cancer (CRC) is fascinating to the public at large. Here, a simple and label-free urine test based on surface-enhanced Raman spectroscopy (SERS) was employed for CRC detection. Significant spectral differences among normal, stages I-II, and stages III-IV CRC urines were observed. Using discriminant function analysis, the diagnostic sensitivities of 95.8%, 80.9%, and 84.3% for classification of normal, stages I-II, and stages III-IV CRC were achieved in training model, indicating the great promise of urine SERS as a rapid, convenient and noninvasive method for CRC staging detection.

Although considerable progress has been achieved in the preparation of uniform hydrous TiO

Background To investigate the feasibility of a knowledge-based automated intensity-modulated radiation therapy (IMRT) planning technique for locally advanced nasopharyngeal carcinoma (NPC) radiotherapy. Methods One hundred forty NPC patients treated with definitive radiation therapy with the step-and-shoot IMRT techniques were retrospectively selected and separated into a knowledge library (n = 115) and a test library (n = 25). For each patient in the knowledge library, the overlap volume histogram (OVH), target volume histogram (TVH) and dose objectives were extracted from the manually generated plan. 5-fold cross validation was performed to divide the patients in the knowledge library into 5 groups before validating one group by using the other 4 groups to train each neural network (NN) machine learning models. For patients in the test library, their OVH and TVH were then used by the trained models to predict a corresponding set of mean dose objectives, which were subsequently used to generate automated plans (APs) in Pinnacle planning system via an in-house developed automated scripting system. All APs were obtained after a single step of optimization. Manual plans (MPs) for the test patients were generated by an experienced medical physicist strictly following the established clinical protocols. The qualities of the APs and MPs were evaluated by an attending radiation oncologist. The dosimetric parameters for planning target volume (PTV) coverage and the organs-at-risk (OAR) sparing were also quantitatively measured and compared using Mann-Whitney U test and Bonferroni correction. Results APs and MPs had the same rating for more than 80% of the patients (19 out of 25) in the test group. Both AP and MP achieved PTV coverage criteria for no less than 80% of the patients. For each OAR, the number of APs achieving its criterion was similar to that in the MPs. The AP approach improved planning efficiency by greatly reducing the planning duration to about 17% of the MP (9.85 ± 1.13 min vs. 57.10 ± 6.35 min). Conclusion A robust and effective knowledge-based IMRT treatment planning technique for locally advanced NPC is developed. Patient specific dose objectives can be predicted by trained NN models based on the individual’s OVH and clinical TVH goals. The automated planning scripts can use these dose objectives to efficiently generate APs with largely shortened planning time. These APs had comparable dosimetric qualities when compared to our clinic’s manual plans.

Nanozymes, nanoparticles that mimic the natural activity of enzymes, are intriguing academically and are important in the context of the Origin of Life. However, current nanozymes offer mimicry of a narrow range of mammalian enzymes, near-exclusively performing redox reactions. We present an unexpected discovery of non-proteinaceous enzymes based on metals, metal oxides, 1D/2D-materials, and non-metallic nanomaterials. The specific novelty of these findings lies in the identification of nanozymes with apparent mimicry of diverse mammalian enzymes, including unique pan-glycosidases. Further novelty lies in the identification of the substrate scope for the lead candidates, specifically in the context of bioconversion of glucuronides, that is, human metabolites and privileged prodrugs in the field of enzyme-prodrug therapies. Lastly, nanozymes are employed for conversion of glucuronide prodrugs into marketed anti-inflammatory and antibacterial agents, as well as "nanozyme prodrug therapy" to mediate antibacterial measures.

Two canonical discriminant functions and the Classification results of SERS spectra prediction of the three urine types in validation dataset

The selective oxidation of primary alcohols to aldehydes by O 2 instead of stoichiometric oxidants (for example, Mn VII , Cr VI , and Os IV ) is an important but challenging process. Most heterogeneous catalytic systems (thermal and photocatalysis) require noble metals or harsh reaction conditions. Here we show that the Bi 24 O 31 Br 10 (OH) δ photocatalyst is very efficient in the selective oxidation of a series of aliphatic (carbon chain from C 1 to C 10 ) and aromatic alcohols to their corresponding aldehydes/ketones under visible-light irradiation in air at room temperature, which would be challenging for conventional thermal and light-driven processes. High quantum efficiencies (71 % and 55 % under 410 and 450 nm irradiation) are reached in a representative reaction, the oxidation of isopropanol. We propose that the outstanding performance of the Bi 24 O 31 Br 10 (OH) δ photocatalyst is associated with basic surface sites and active lattice oxygen that boost the dehydrogenation step in the photo-oxidation of alcohols.

Herein, an innovative approach was developed by using stable, lead-free halide perovskite for solar-driven organic synthesis. The ring-opening reaction of epoxides was chosen as a model system for the synthesis of value-added β-alkoxy alcohols, which require energy-intensive process conditions and corrosive, strong acids for conventional synthesis. The developed concept included the in situ preparation of Cs

The selective oxidation of primary alcohols to aldehydes by O

Photocatalytic organic conversions involving a hydrogen transfer (HT) step have attracted much attention, but the efficiency and selectivity under visible light irradiation still needs to be significantly enhanced. Here we have developed a noble metal-free, basic-site engineered bismuth oxybromide [Bi24O31Br10(OH)] that can accelerate the photocatalytic HT step in both reduction and oxidation reactions, i.e., nitrobenzene to azo/azoxybenzene, quinones to quinols, thiones to thiols, and alcohols to ketones under visible light irradiation and ambient conditions. Remarkably, quantum efficiencies of 42% and 32% for the nitrobenzene reduction can be reached under 410 and 450 nm irradiation, respectively. The Bi24O31Br10(OH) photocatalyst also exhibits excellent performance in up-scaling and stability under visible light and even solar irradiation, revealing economic potential for industrial applications.

// Yuanji Xu 1,* , Mingwei Zhang 1,* , Youping Xiao 1,2 , Jingfeng Zong 3,4 , Sufang Qiu 1,3,4 , Penggang Bai 3,4 , Yitao Dai 3,4 , Lin Zhou 1 , Xiaolin Chen 1 , Wei Zheng 3,4 , Yunbin Chen 1,2 , Shaojun Lin 3,4 and Jianji Pan 1,3,4 1 The Shengli Clinical Medical College of Fujian Medical University, Fuzhou, China 2 Department of Radiology, Teaching Hospital of Fujian Medical University, Fujian Provincial Cancer Hospital, Fuzhou, China 3 Department of Radiation Oncology, Teaching Hospital of Fujian Medical University, Fujian Provincial Cancer Hospital, Fuzhou, China 4 Fujian Provincial Key Laboratory of Translational Cancer Medicine, Fuzhou, China * These authors have contributed equally to this work Correspondence to: Jianji Pan, email: // Shaojun Lin, email: // Keywords : nasopharyngeal carcinoma, parotid area lymph node metastases, tumor characteristics, oncologic outcomes Received : October 20, 2015 Accepted : February 15, 2016 Published : February 24, 2016 Abstract The parotid area lymph node (PLN) is an uncommon site of metastasis originating from nasopharyngeal carcinoma (NPC). The study aimed to investigate clinical characteristics and outcomes of patients with preliminarily diagnosed NPC with PLN metastases. Here we retrospectively reviewed Magnetic resonance imaging (MRI) scans of 2221 patients with untreated nonmetastatic NPC who received intensity-modulated radiation therapy (IMRT). Finally, 64 (2.9%) patients were identified with PLN metastases, of which, 34 received PLN-sparing IMRT and 30 received PLN-radical IMRT. We also found that 42.2% had N3 disease and 95.3% had stages III-IVb. PLN metastases on MRI were characterized by ipsilateral retropharyngeal lymph node (RLN) or level II nodal extracapsular spread (ECS), ipsilateral giant cervical nodes, ipsilateral parapharyngeal extension, or solitary parotid metastasis. The 5-year overall survival, distant metastasis-free survival, regional relapse-free survival, and parotid relapse-free survival rates were 70.4%, 64.3%, 76.7%, and 87.9%, respectively. Distant metastases were the main cause of treatment failure and death. Using PLN-sparing IMRT, sparing PLN with minimal axial diameter of

In this work, the unconsolidated carbon-nitride-layer close-wrapped nanodiamond (H-ND) hybrid has been successfully synthesized by a facile two-step approach including the mechanical milling of ND powder and hexamethylenetetramine and the followed pyrolysis of hexamethylenetetramine. The unique microstructure and surface chemistry characteristics of the nanohybrid have been identified by employing diverse characterization techniques including field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), N2 adsorption desorption (BET), X-ray diffraction (XRD), Raman spectroscopy (Raman), and X-ray photoelectron spectroscopy (XPS) analyses. Benefiting from the intensified synergistic effect between carbon nitride and nanodiamond, the as-synthesized H-ND hybrid carbocatalyst shows remarkably higher catalytic activity for oxidant- and steam-free direct dehydrogenation (DDH) of ethylbenzene than the nanodiamond (ND) and the previously developed mesoporous carbon...

A facile and scalable approach to efficiently tune microstructure and surface chemical properties of N-doped carbocatalysts through the controlled glucose hydrothermal treatment with diverse parameters and subsequent pyrolysis of pretreated carbonaceous materials with melamine (GHT-PCM) was presented. Various characterization techniques including high resolution transmission electron microscopy (HRTEM), N2 adsorption desorption (BET), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy (Raman), and fourier transform infrared spectroscopy (FTIR) were employed to investigate the effect of prior GHT on the microstructure and surface chemical properties of N-doped carbocatalysts, as well as to reveal the relationship between catalyst nature and catalytic performance in oxidant- and steam-free direct dehydrogenation (DDH) of ethylbenzene for styrene production. It was found that the GHT process and its conditions significantly affect microstructure and surface chemical properties of the N-doped carbocatalysts, which subsequently influences their catalytic performance in DDH reaction dramatically. Interestingly, the prior GHT can remove the carbon nitride layer formed on parent nanocarbon in the process of melamine pyrolysis, produce structural defects, and tune surface element component, through the “detonation” of polysaccharide coating on nanocarbon. The as-prepared N-doped CNT (M-Glu-CNT) by the established GHT-PCM approach demonstrates higher catalytic performance (4.6 mmol g−1h−1 styrene rate with 98% selectivity) to the common N-doped CNT (M-CNT, 3.4 mmol g−1 h−1 styrene rate with 98.2% selectivity) as well as to pristine CNT (2.8 mmol g−1 h−1 styrene rate with 96.8% selectivity), mainly ascribed to increased structural defects, enriched surface ketonic CO groups, and improved basic properties from N-doping on the M-Glu-CNT, those strongly depend on GHT conditions. The excellent catalytic performance of the developed M-Glu-CNT catalyst endows it with great potential for future clean production of styrene via oxidant- and steam-free conditions. Moreover, the directed GHT-PCM strategy can be extended to the other N-doped carbonaceous materials with enhanced catalytic performance in diverse reactions by tuning their microstructure and surface chemistry. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2543–2561, 2015

A facile and scalable approach for fabricating structural defect-rich nitrogen-doped carbon nanotubes (MCSA-CNTs) through explosive decomposition of melamine-cyanuric acid supramolecular assembly is presented. In comparison to pristine carbon nanotubes, MCSA-CNT exhibits significantly enhanced catalytic performance in oxidant- and steam-free direct dehydrogenation of ethylbenzene, demonstrating the potential for metal-free clean and energy-saving styrene production. This finding also opens a new horizon for preparing highly-efficient carbocatalysts rich in structural defect sites for diverse transformations.

Owing to their unique structural features and surface properties, graphene and nanodiamond have attracted tremendous attention in diverse fields. However, restacking of graphene and reagglomeration of dispersed nanodiamond inevitably depress their catalytic properties. Herein, inspired by the historic discovery of “pillared clay”, we successfully realized the simultaneous inhibition of their restacking by fabricating a N-doped mesoporous graphene/nanodiamond (N-RGO/ND) nanocomposite by a facile wet-chemical approach. The electrocatalytic oxygen reduction reaction (ORR) and the thermocatalytic oxidant-free and steam-free direct dehydrogenation (DDH) of ethylbenzene were used to examine its catalytic properties. The nanocomposite showed synergistically improved catalytic DDH and electrocatalytic ORR activity relative to that of the individual components, which can be ascribed to synergy between graphene and nanodiamond and to the large surface area, well-ordered mesoporous structure, small crystalline size, and rich defect and CO surface features. Moreover, the developed synthetic strategy in this work can be extended to diverse N-doped nanocomposites from dispersion-required carbon precursors.

A novel and efficient nitrogen-doped carbon nanotube (A-M-CNT) catalyst has been prepared by a facile two-step method, including prior air activation and subsequent pyrolysis of the carbon nanotubes with melamine. The as-synthesized A-M-CNT affords superior catalytic activity to the nitrogen-doped CNT without air activation (M-CNT) and pristine CNT, ascribed to its unique microstructure and surface chemical properties.

This work presents an efficient and low-cost one-step strategy for simultaneously N-doping and increasing surface ketonic CO groups and structural defects of a N-doped carbon nanotube (HN-CNT) through the explosive decomposition of hexamethylenetetramine (HTA) nitrate, a low-cost N,O-containing organic compound. The as-synthesized HN-CNT demonstrates a 1.64 and 2.19 times higher steady-state styrene rate with 98.5% selectivity towards styrene for direct dehydrogenation (DDH) than that of the parent CNT and H-CNT prepared by the similar pyrolysis procedure to that for the HN-CNT except for replacing HTA nitrate with HTA.

O,N-doped carbon nanotubes with increased structural defects and enriched surface ketonic CO groups (MN-CNT), prepared by a facile and low-cost one-step strategy, demonstrate unexpected catalytic performance in direct dehydrogenation of ethylbenzene for styrene production with clean and energy-saving features. This work paves a new avenue for preparing other highly-efficient carbocatalysts in diverse organic transformations.

A novel N-doped activated carbon (AC) based nanostructure decorated with nanotubes (N-CNT-AC) has been successfully fabricated through a facile and scalable approach involving the mechanical milling and subsequent solid pyrolysis of the low-cost and commercially available AC and melamine. Various characterization techniques including high resolution transmission electron microscopy, X-ray diffraction, nitrogen adsorption, X-ray photoelectron spectroscopy, Raman spectroscopy and Fourier transform infrared spectroscopy were employed to reveal the relationship between catalyst features and catalytic performance in the oxidant- and steam-free direct dehydrogenation (DDH) of ethylbenzene to styrene. Although the as-synthesized AC-based hybrid nanostructure has a much lower surface area (397.0 cm2 g−1) and pore volume (0.17 cm3 g−1) than the parent AC (777.1 cm2 g−1 surface area and 0.4 cm3 g−1 pore volume), it demonstrates 1.74 and 3.67 times the steady-state styrene rate of the per gram parent AC and the industrially-used K–Fe catalyst, respectively, for the DDH reaction, which is ascribed to the promoting effect of the unique hybrid microstructure, the surface rich CO group and defect/edge feature, the increased basic properties through N-introduction into the hybrid nanostructure, the small size of the graphitic crystallite, as well as the inherent high surface and large porosity of the AC-based materials. The in situ Fourier transform infrared spectroscopy measurement suggests a lower activation energy over the developed novel N-doped AC-based hybrid nanostructure for the DDH reaction than over the parent AC. Interestingly, the developed hybrid nanocomposite exhibits a much superior selectivity for styrene production compared to the parent AC, which is ascribed to the N-doping into the AC-based matrix. The developed N-doped AC-based hybrid nanostructure catalyst could be a potential candidate for catalytic styrene production via steam- and oxidant-free direct dehydrogenation of ethylbenzene.