Bi-modified Cu-Based Catalysts for Acetylene Hydrogenation: Leveraging Dispersion and Hydrogen Spillover.

Removing trace acetylene from the ethylene stream through selective hydrogenation is a crucial process in the production of polymer-grade ethylene. However, achieving high selectivity while maintaining high activity remains a significant challenge, especially for nonprecious metal catalysts. Herein, the trade-off between activity and selectivity is solved by synergizing enhanced dispersion and hydrogen spillover. Specifically, a bubbling method is proposed for preparing SiO2-supported copper and/or bismuth carbonate with high dispersion, which is then employed to synthesize highly dispersed Bi-modified CuxC-Cu catalyst. The catalyst displays outstanding catalytic performance for acetylene selective hydrogenation, achieving acetylene conversion of 100% and ethylene selectivity of 91.1% at 100 °C. The high activity originates from the enhanced dispersion, and the exceptional selectivity is due to the enhanced spillover capacity of active hydrogen from CuxC to Cu, which is promoted by the Bi addition. The results offer an avenue to design efficient catalysts for selective hydrogenation from nonprecious metals.

Association of lysine pathway metabolites with moyamoya disease.

BACKGROUND AND OBJECTIVE: Lysine and its pathway metabolites have been identified as novel biomarkers for metabolic and vascular diseases. The role of them in the identification of moyamoya disease (MMD) has not been elucidated. This study aimed to determine the association between lysine pathway metabolites and the presence of MMD. METHODS: We prospectively enrolled 360 MMD patients and 89 healthy controls from September 2020 to December 2021 in Beijing Tiantan Hospital. Serum levels of lysine, pipecolic acid and 2-aminoadipic acid were measured by liquid chromatography-mass spectrometry. We employed logistic regression and restricted cubic spline to explore the association between these metabolites and the presence of MMD. Stratified analyses were also conducted to test the robustness of results. RESULTS: We observed that lysine levels in MMD patients were significantly higher and pipecolic acid levels were significantly lower compared to HCs (both p < 0.001), while no difference was found in the level of 2-AAA between both groups. When comparing metabolites by quartiles, elevated lysine levels were linked to increased odds for MMD (the fourth quartile [Q4] vs the first quartile [Q1]: odds ratio, 3.48, 95%CI [1.39-8.75]), while reduced pipecolic acid levels correlated with higher odds (Q4 vs Q1: odds ratio, 0.08; 95 % CI [0.03-0.20]). The restricted cubic spline found a L-shaped relationship between pipecolic acid level and the presence of MMD, with a cutoff point at 2.52 µmol/L. Robust results were also observed across subgroups. CONCLUSION: Elevated lysine levels were correlated with increased odds of MMD presence, while lower pipecolic acid levels were associated with higher odds of the condition. These results suggest potential new biomarkers for the identification of MMD. CLINICAL TRIAL REGISTRY NUMBER: URL: https://www.chictr.org.cn/. Unique identifier: ChiCTR2200061889.

miR-10a induces inflammatory responses in epileptic hippocampal neurons of rats via PI3K/Akt/mTOR signaling pathway.

Epilepsy is a common chronic neurological disorder worldwide. MicroRNAs (miRNAs) play an important role in the pathogenesis of epilepsy. However, the mechanism of the regulatory effect of miR-10a on epilepsy is unclear. In this study, we investigated the effect of miR-10a expression on the PI3K/Akt/mTOR signaling pathway and inflammatory cytokines in epileptic hippocampal neurons of rats. The miRNA differential expression profile of rat epileptic brain was analyzed using bioinformatic approaches. Neonatal Sprague-Dawley rat hippocampal neurons were prepared as epileptic neuron models in vitro by replacing culture medium with magnesium-free extracellular solution. The hippocampal neurons were transfected with miR-10a mimics, and transcript levels of miR-10a, PI3K, Akt and mTOR were detected by quantitative reverse transcription-PCR, and PI3K, mTOR, Akt, TNF-α, IL-1ß, IL-6 protein expression levels were detected by Western blot. Cytokines secretory levels were detected by ELISA. Sixty up-regulated miRNAs were identified in the hippocampal tissue of epileptic rats and might affect the PI3K-Akt signaling pathway. In the epileptic hippocampal neurons model, the expression levels of miR-10a were significantly increased, with decreasing levels of PI3K, Akt and mTOR, and increasing levels of TNF-α, IL-1ß and IL-6. The miR-10a mimics promoted the expression of TNF-α, IL-1ß and IL-6. Meanwhile, miR-10a inhibitor activated PI3K/Akt/mTOR pathway and inhibited cytokines secretion. Finally, cytokine secretion was increased by treated with PI3K inhibitor and miR-10a inhibitor. The miR-10a may promote inflammatory responses in rat hippocampal neurons by inhibiting the PI3K/Akt/mTOR pathway, suggesting that miR-10a may be one of the target therapeutic molecules for epilepsy treatment.

A highly active catalyst derived from CuO particles for selective hydrogenation of acetylene in large excess ethylene.

The removal of acetylene impurities is indispensable in the production of ethylene. An Ag-promoted Pd catalyst is industrially used to remove acetylene impurities by selective hydrogenation. It is highly desirable to replace Pd with non-precious metals. In the present investigation, CuO particles, which are most frequently used as the precursors for Cu-based catalysts, were prepared through the solution-based chemical precipitation method and used to prepare high-performance catalysts for selective hydrogenation of acetylene in large excess ethylene. The non-precious metal catalyst was prepared by treating CuO particles with acetylene-containing gas (0.5 vol% C2H2/Ar) at 120 °C and subsequent hydrogen reduction at 150 °C. The obtained catalyst was tested in selective hydrogenation of acetylene in a large excess of ethylene (0.72 vol% CH4 as the internal standard, 0.45 vol% C2H2, 88.83 vol% C2H4, 10.00 vol% H2). It exhibited significantly higher activity than the counterpart of Cu metals, achieving 100% conversion of acetylene without ethylene loss at 110 °C and atmospheric pressure. The characterization by means of XRD, XPS, TEM, H2-TPR, CO-FTIR, and EPR verified the formation of an interstitial copper carbide (CuxC), which was responsible for the enhanced hydrogenation activity.

Application of blood flow restriction in hypoxic environment augments muscle deoxygenation without compromising repeated sprint exercise performance.

NEW FINDINGS: What is the central question of this study? Does applying blood flow restriction during the rest periods of repeated sprint exercise in a hypoxic environment lead to greater local hypoxia within exercising muscles without compromising training workload? What is the main finding and its importance? Repeated sprint exercise with blood flow restriction administered during rest periods under systemic hypoxia led to severe local hypoxia within the exercised muscles without a reduction in power output. The maintained power output might be due to elevated neuromuscular activation. Accordingly, the proposed repeated sprint exercise in the current study may be an effective training modality. ABSTRACT: Repeated sprint exercise (RSE) is a popular training modality for a wide variety of athletic activities. The purpose of this study was to assess the combined effects of systemic hypoxia and blood flow restriction (BFR) on muscle deoxygenation and RSE performance. Twelve healthy young men performed a standard RSE training modality (five sets of 10 s maximal sprint with a 60 s rest) under four different conditions: (1) normoxic control (NC), normoxia (N, 20.9%) + control BFR (C, 0 mmHg); (2) normoxic BFR (NB), normoxia (N, 20.9%) + BFR (B, 140 mmHg); (3) hypoxic control (HC), hypoxia (H, 13.7%) + control BFR (C, 0 mmHg); and (4) hypoxic BFR (HB): hypoxia (H, 13.7%) + BFR (B, 140 mmHg). BFR was only administered during the rest period of the respective RSE trials. In the local exercising muscles, muscle oxygen saturation ( Sm O 2 $\textit{Sm}{O}_{2}$ ) and neuromuscular activity were measured using near-infrared spectroscopy and surface electromyography, respectively. SmO2 was lower in systemic hypoxia conditions relative to normoxia conditions (P < 0.05). A rther decrease in SmO2 was observed in HB relative to HC (Set 1: HC 70.0 ± 17.5 vs. HB 57.4 ± 11.3%, P = 0.001; Set 4: HC 67.5 ± 14.6 vs. HB 57.0 ± 12.0%, P = 0.013; Set 5: HC 61.0 ± 15.3 vs. HB 47.7 ± 11.9%, P < 0.001). No differences in RSE performance were observed between any of the conditions (P > 0.05). Interestingly, an elevated neuromuscular activity was seen in response to the BFR, particularly during conditions of systemic hypoxia (P < 0.05). Thus, RSE with BFR administered during rest periods under systemic hypoxia led to severe local hypoxia without compromising training workload.

An efficient NiCu@C/Al2O3 catalyst for selective hydrogenation of acetylene.

The development of non-noble metal catalysts for selective hydrogenation still remains a challenge. Herein, NiCu@carbon core-shell nanoparticles supported on Al2O3 (NiCu@C/Al2O3) were prepared, which showed enhanced catalytic performance of acetylene-selective hydrogenation in comparison with NiCu/Al2O3 without carbon encapsulation. In detail, NiCu@C/Al2O3 displayed high ethylene selectivity (>86%) even at an acetylene conversion of 100% and excellent stability (>90 h). Thus, NiCu@C/Al2O3 exhibited great potential as an alternative to Pd-based catalysts for acetylene-selective hydrogenation.

Topical Analgesic Containing Methyl Salicylate and L-Menthol Accelerates Heat Loss During Skin Cooling for Exercise-Induced Hyperthermia.

Hyperthermia impairs physical performance and, when prolonged, results in heat stroke or other illnesses. While extensive research has investigated the effectiveness of various cooling strategies, including cold water immersion and ice-suit, there has been little work focused on overcoming the cutaneous vasoconstriction response to external cold stimulation, which can reduce the effectiveness of these treatments. Over-the-counter (OTC) topical analgesics have been utilized for the treatment of muscle pain for decades; however, to date no research has examined the possibility of taking advantage of their vasodilatory functions in the context of skin cooling. We tested whether an OTC analgesic cream containing 20% methyl salicylate and 6% L-menthol, known cutaneous vasodilators, applied to the skin during skin cooling accelerates heat loss in exercise-induced hyperthermia. Firstly, we found that cutaneous application of OTC topical analgesic cream can attenuate cold-induced vasoconstriction and enhance heat loss during local skin cooling. We also revealed that core body heat loss, as measured by an ingestible telemetry sensor, could be accelerated by cutaneous application of analgesic cream during ice-suit cooling in exercise-induced hyperthermia. A blunted blood pressure response was observed during cooling with the analgesic cream application. Given the safety profile and affordability of topical cutaneous analgesics containing vasodilatory agents, our results suggest that they can be an effective and practical tool for enhancing the cooling effects of skin cooling for hyperthermia.

Hydrogenative Ring-Rearrangement of Furfural to Cyclopentanone over Pd/UiO-66-NO2 with Tunable Missing-Linker Defects.

Upgrading furfural (FAL) to cyclopentanone (CPO) is of great importance for the synthesis of high-value chemicals and biomass utilization. The hydrogenative ring-rearrangement of FAL is catalyzed by metal-acid bifunctional catalysts. The Lewis acidity is a key factor in promoting the rearrangement of furan rings and achieving a high selectivity to CPO. In this work, highly dispersed Pd nanoparticles were successfully encapsulated into the cavities of a Zr based MOF, UiO-66-NO2, by impregnation using a double-solvent method (DSM) followed by H2 reduction. The obtained Pd/UiO-66-NO2 catalyst showed a significantly better catalytic performance in the aforementioned reaction than the Pd/UiO-66 catalyst due to the higher Lewis acidity of the support. Moreover, by using a thermal treatment. The Lewis acidity can be further increased through the creating of missing-linker defects. The resulting defective Pd/UiO-66-NO2 exhibited the highest CPO selectivity and FAL conversion of 96.6% and 98.9%, respectively. In addition, the catalyst was able to maintain a high activity and stability after four consecutive runs. The current study not only provides an efficient catalytic reaction system for the hydrogenative ring-rearrangement of furfural to cyclopentanone but also emphasizes the importance of defect sites.

Copper-Based Catalysts for Selective Hydrogenation of Acetylene Derived from Cu(OH)2.

Replacing precious metals with cheap metals in catalysts is a topic of interest in both industry and academia but challenging. Here, a selective hydrogenation catalyst was prepared by thermal treatment of Cu(OH)2 nanowires with acetylene-containing gas at 120 °C followed by hydrogen reduction at 150 °C. The characterization by means of transmission electron microscopy observation, X-ray diffraction, and X-ray photoelectron spectroscopy revealed that two crystallites were present in the resultant catalyst. One of the crystal phases was metal Cu, whereas the other crystal phase was ascribed to an interstitial copper carbide (Cu x C) phase. The reduction of freshly prepared copper (II) acetylide (CuC2) at 150 °C also afforded the formation of Cu and Cu x C crystallites, indicating that CuC2 was the precursor or an intermediate in the formation of Cu x C. The prepared catalysts consisting of Cu and Cu x C exhibited a considerably high hydrogenation activity at low temperatures in the selective hydrogenation of acetylene in the ethylene stream. In the presence of a large excess of ethylene, acetylene was completely converted at 110 °C and atmospheric pressure with an ethane selectivity of <15%, and the conversion and selectivity were constant in a 260 h run.

Preparation of an Unsupported Copper-Based Catalyst for Selective Hydrogenation of Acetylene from Cu2O Nanocubes.

Designing cheap, earth-abundant, and nontoxic metal catalysts for acetylene hydrogenation is of pivotal importance, but challenging. Here, a nonprecious metal catalyst for selective hydrogenation of acetylene in excess ethylene was prepared from Cu2O nanocubes. The preparation includes two steps: (1) thermal treatment in acetylene-containing gas at 160 °C and (2) hydrogen reduction at 180 °C. The resultant catalyst showed outstanding performance at low temperature (80-100 °C) and 0.1-0.5 MPa pressure, completely converting acetylene with a low selectivity to undesired ethane (<20%). The characterization results of high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy corroborated that the formation of an interstitial copper carbide (CuxC) might give rise to significantly enhanced hydrogenation activity. Preliminary density functional theory calculation demonstrated that the lattice spacing of Cu3C was nearly identical to that of the new CuxC crystallite measured in HRTEM and determined by XRD. The calculated dissociation energy of hydrogen on Cu3C(0001) was considerably lower than that on Cu(111), suggesting superior hydrogenation activity of Cu3C(0001). It is experimentally verified that copper(I) acetylide (Cu2C2) might be the precursor of CuxC. Cu2C2 underwent partial hydrogenation to fabricate CuxC crystallites and the thermal decomposition to Cu and carbon materials in parallel.

Transition Metal Oxodiperoxo Complex Modified Metal-Organic Frameworks as Catalysts for the Selective Oxidation of Cyclohexane.

In this work, a series of modified metal-organic frameworks (MOFs) have been prepared by pre- and post-treatment with transition metal oxodiperoxo complexes (MoO(O2)2, WO(O2)2, and KVO(O2)2). The obtained materials are characterized by XRD, FTIR, SEM, TEM, inductively coupled plasma atomic emission spectrometry (ICP-AES), and X-ray photoelectron spectroscopy (XPS), as well as by N2 adsorption/desorption measurement. The characterization results show that transition metal oxodiperoxo complexes are uniformly incorporated into the MOF materials without changing the basic structures. The performance of cyclohexane oxidation on metal oxodiperoxo complex modified MOFs are evaluated. UiO-67-KVO(O2)2 shows the best performance for cyclohexane oxidation, with 78% selectivity to KA oil (KA oil refers to a cyclohexanol and cyclohexanone mixture) at 9.4% conversion. The KA selectivity is found to depend on reaction time, while hot-filtration experiments indicates that the catalytic process is heterogeneous with no leaching of metal species.

Adversarial Learning for Joint Optimization of Depth and Ego-Motion.

In recent years, supervised deep learning methods have shown a great promise in dense depth estimation. However, massive high-quality training data are expensive and impractical to acquire. Alternatively, self-supervised learning-based depth estimators can learn the latent transformation from monocular or binocular video sequences by minimizing the photometric warp error between consecutive frames, but they suffer from the scale ambiguity problem or have difficulty in estimating precise pose changes between frames. In this paper, we propose a joint self-supervised deep learning pipeline for depth and ego-motion estimation by employing the advantages of adversarial learning and joint optimization with spatial-temporal geometrical constraints. The stereo reconstruction error provides the spatial geometric constraint to estimate the absolute scale depth. Meanwhile, the depth map with an absolute scale and a pre-trained pose network serves as a good starting point for direct visual odometry (DVO). DVO optimization based on spatial geometric constraints can result in a fine-grained ego-motion estimation with the additional backpropagation signals provided to the depth estimation network. Finally, the spatial and temporal domain-based reconstructed views are concatenated, and the iterative coupling optimization process is implemented in combination with the adversarial learning for accurate depth and precise ego-motion estimation. The experimental results show superior performance compared with state-of-the-art methods for monocular depth and ego-motion estimation on the KITTI dataset and a great generalization ability of the proposed approach.

Interwoven Molecular Chains Obtained by Ionic Self-Assembly of Two Iron(III) Porphyrins with Opposite and Mismatched Charges.

We report ionic self-assembly of positively charged FeIII meso-tetra(N-methyl-4-pyridyl) porphyrin (FeIIINMePyP) with negatively charged FeIII meso-tetra(4-sulfonatophenyl) porphyrin (FeIIITPPS4), leading to the formation of flower-like nanostructures composed of unprecedented three-dimensional (3D) entangled chains of porphyrin dimers. Molecular dynamics (MD) simulations show that the 3D entanglement of porphyrin chains closely correlates to mismatched charges present in porphyrin dimers like [FeIII(H2O)2NMePyP]5+/[FeIII(H2O)2TPPS4]3- that requires extra interactions or entanglement with neighboring ones to achieve electric neutrality. Interestingly, the interwoven chains bring in excellent thermal stability as evidenced by well maintenance of the flower-like morphology after pyrolysis at 775 °C in argon, which is in good agreement of high-temperature MD simulations. Meanwhile, heat treatment of the flower-like porphyrin nanostructure leads to the formation of a non-noble metal electrocatalyst (NNME) with largely inherited morphology. This exemplifies a new approach by combining ionic self-assembly with subsequent pyrolysis for the synthesis of NNMEs with desired control over the morphology of template-free NNMEs that has rarely been achieved prior to this study. Furthermore, our electrocatalyst exhibits excellent activity and durability toward oxygen reduction reaction as well as much better methanol tolerance compared with commercial Pt/C in alkaline solutions.

Construction of 2D/2D BiVO4/g-C3N4 nanosheet heterostructures with improved photocatalytic activity.

In this work, a two dimensional (2D)/2D BiVO4/g-C3N4 heterostructure with strong interfacial interaction was successfully constructed. The as-prepared BiVO4/g-C3N4 heterostructures exhibit distinctly enhanced visible light photocatalytic performance toward the degradation of Rodanmin B (RhB) and water splitting to oxygen (O2) as compared to pristine g-C3N4 and BiVO4, which can be attributed to the strong interfacial interaction and abundant 2D coupling interfaces, facilitating efficient charge separation. Among the composites with various ratios, the BiVO4-10/g-C3N4 sample achieves the optimum photocatalytic activity for the degradation of RhB, and reached 15.8 and 4.3 times compared to pure g-C3N4 and BiVO4. Moreover, the corresponding composite reached a high O2-production rate of 0.97 µmol h-1 under visible light irradiation, which is 12.1 and 2.8 times higher than that of pure g-C3N4 and BiVO4, respectively. It was demonstrated that the efficiency of electron-hole separation has certain contribution to the photocatalytic performance over the BiVO4/g-C3N4 heterostructure. The present study suggests that the unique 2D/2D BiVO4/g-C3N4 hybrid nanosheets should be conducive to improve the photocatalytic performance of organic pollutant degradation and water splitting.

Cost-effective promoter-doped Cu-based bimetallic catalysts for the selective hydrogenation of C2H2 to C2H4: the effect of the promoter on selectivity and activity.

In order to probe into the effect of the promoter on the selectivity and activity towards C2H4 formation in the selective hydrogenation of C2H2 over cost-effective Cu-based bimetallic catalysts, different metal promoter M-modified Cu catalysts including Ni, Ag, Au, Pt, Pd and Rh have been employed to fully investigate the selective hydrogenation of C2H2 using density functional theory calculations together with microkinetic modeling. The results show that the adsorption ability of C2H2 is far stronger than that of C2H4 on different Cu-based catalysts, which favors the activation and hydrogenation of C2H2. The type of promoter obviously affects the preferable pathway of C2H2 selective hydrogenation, and ultimately alters the selectivity of the products; only on PdCu(211) and AgCu(211) surfaces, the C2H4 desorption pathway is the most favorable for gaseous C2H4 formation, suggesting that the promoter Pd or Ag has good selectivity towards C2H4 formation. The catalytic activity towards C2H4 formation follows the order PdCu(211) > PtCu(211) > NiCu(211) > RhCu(211) > AgCu(211) > AuCu(211) > Cu(211), indicating that the promoter can obviously increase the catalytic activity towards C2H4 formation compared to the Cu catalyst alone. Thus, the promoter Pd-modified Cu catalysts exhibit the highest catalytic activity and selectivity for C2H2 hydrogenation to C2H4. This work provides a method to evaluate and obtain the type of promoter with the best activity and selectivity in the selective hydrogenation of C2H2.

Phase Effect of NixPy Hybridized with g-C3N4 for Photocatalytic Hydrogen Generation.

The use of noble metal-free nickel phosphides (NixPy) as suitable cocatalysts in photocatalytic hydrogen (H2) generation has gained a lot of interest. In this paper, for the first time, three different crystalline phases of nickel phosphides, Ni2P, Ni12P5, and Ni3P, were synthesized and then hybridized with g-C3N4 to investigate the phase effect of NixPy on photocatalytic H2 generation. It has been found that all three phases of NixPy work as effective cocatalysts for the enhancement of visible light H2 generation with g-C3N4. The effective charge transfer between g-C3N4 and NixPy, demonstrated by photoelectrochemical properties, photoluminescence, and time-resolved diffused reflectance, contributes to the enhanced photocatalytic H2 generation performance. Interestingly, Ni2P/g-C3N4 showed the highest photocatalytic activity among the three NixPy/g-C3N4. NixPy with a higher ratio of phosphorus (Ni2P) can accelerate charge transfer and provide more Ni-P bonds, leading to a preferable H2 generation performance.

Disproportionation of hypophosphite and phosphite.

The disproportionation of NaH2PO2, NaH2PO3, Na2HPO3 and their mixtures was studied by TG-DSC, XRD and 31P NMR. NaH2PO2 reacted in three steps to yield PH3, Na5P3O10 and H2 by disproportionation and oxidation with water released in condensation reactions. In the first step at 310 °C NaH2PO2 reacted to yield PH3, Na2H2P2O5, Na2HPO3, Na4P2O7 and H2. H2 rather than H2O was the coproduct of the disproportionation, because H2O oxidized hypophosphite and phosphite at elevated temperatures, in agreement with DFT results that show that the reaction of H3PO3 with H2O is exothermic. The oxidation of phosphite by H2O has a twofold effect on gas formation. First, it diminishes gas formation because water is not released and, second, because H2O oxidizes phosphite, less phosphite is available for disproportionation to phosphate and, thus, less PH3 is formed. As a consequence, the maximum PH3 efficiency in the disproportionation of NaH2PO2 was not 50% but 40%. Phosphate was never observed, only Na4P2O7, which appeared as a primary product of the oxidation of Na2H2P2O5 by H2O. Na2HPO3 did not react below 450 °C when heated alone, but in the presence of compounds which release H2O it was oxidized to Na4P2O7 below 400 °C. NaH2PO3 first reacted to yield PH3 and Na2H2P2O5 and then to Na5P3O10 and Na3P3O9. Heating a 1 : 1 mixture of NaH2PO3 and Na2HPO3 led to PH3, Na2H2P2O5 and Na2HPO3, then to Na4P2O7 and eventually to Na5P3O10 and Na3P3O9. In all cases some red phosphorus was formed by the decomposition of PH3, especially at higher temperatures.

Facile Preparation of Ni2P with a Sulfur-Containing Surface Layer by Low-Temperature Reduction of Ni2P2S6.

Preparation of Ni2P by temperature-programmed reduction (TPR) of a phosphate precursor is challenging because the P-O bond is strong. An alternative approach to synthesizing Ni2P, by reduction of nickel hexathiodiphosphate (Ni2P2S6), is presented. Conversion of Ni2P2S6 into Ni2P occurs at 200-220 °C, a temperature much lower than that required by the conventional TPR method (typically 500 °C). A sulfur-containing layer with a thickness of about 4.7 nm, composed of tiny crystallites, was observed at the surface of the obtained Ni2 P catalyst (Ni2P-S). This is a direct observation of the sulfur-containing layer of Ni2P, or the so-called nickel phosphosulfide phase. Both the hydrodesulfurization activity and the selective hydrogenation performance of Ni2P-S were superior to that of the catalyst prepared by the TPR method, suggesting a positive role of sulfur on the surface of Ni2P-S. These features render Ni2P-S a legitimate alternative non-precious metal catalyst for hydrogenation reactions.

Carbonization of self-assembled nanoporous hemin with a significantly enhanced activity for the oxygen reduction reaction.

The scarcity and high cost of Pt-based electrocatalysts for the oxygen reduction reaction (ORR) hinder the practical application of proton exchange membrane fuel cells (PEMFCs). It is critical to replace platinum with non-noble metal electrocatalysts (NNMEs). Carbonized metalloporphyrins represent an important class of NNMEs, but most metalloporphyrins are costly and the corresponding NNMEs do not possess a high ORR activity. Herein, we report that the self-assembly of inexpensive hemin leads to porous nanomaterials in water under ambient conditions and subsequent heat-treatment of the unprecedented nanoporous hemin results in a magnetic NNME with a much enhanced ORR activity compared with directly carbonized hemin without self-assembly. The improvement of the ORR activity likely originates from the exposure of more ORR active sites, caused by the surface area increase of the nanoporous hemin after carbonization over that of micro-scale pristine hemin crystals. Moreover, the ORR activity of heat-treated nanoporous hemin is actually comparable to that of commercial Pt/C in alkaline solution. Additionally, the carbonized nanoporous hemin is much better than commercial Pt/C in terms of durability and tolerance to methanol. This study opens up a new avenue to the production of inexpensive metalloporphyrin-based NNMEs with a high ORR performance by using a self-assembly method in combination with traditional pyrolysis.