The ability to create highly active and CO‐tolerant platinum‐free catalysts toward alkaline hydrogen oxidation reaction (HOR) represents a significant endeavor to enable commercialization of alkaline fuel cells. This, however, remains a grand challenge. Herein, a robust defective‐carbon‐supported Ru catalyst (denoted as Ru@C) is crafted to achieve efficient and CO‐tolerant HOR in alkaline media via delicately tailoring interfacial chemistry of catalyst. Notably, the degree of defects in the carbon support is the key to tune the interface chemistry. An integrated experimental and density functional theory calculations study demonstrates that the favorable interfacial chemical interaction between Ru and carbon support controlled by the covalently bonded Ru─O─C redistributes the d electrons of Ru and downshiftsits d‐band center, which in turn weakens the hydrogen adsorption and suppresses the Ru 4d→CO 2π* back donation. Consequently, the optimized Ru@C catalyst renders a 6.6‐fold enhancement in mass activity (@25 mV) for alkaline HOR over the conventional Ru/C counterpart, which also outperforms the state‐of‐the‐art catalysts. Intriguingly, the catalyst can tolerate 20 000 ppm CO, far exceeding that of commercial Pt/C and PtRu/C catalysts. This work elucidates the correlation between precisely tailored interfacial chemistry and HOR performance, and is expected to further enlighten the design of advanced catalysts.

Tailoring Interfacial Chemistry of Defective Carbon‐Supported Ru Catalyst Toward Efficient and CO‐Tolerant Alkaline Hydrogen Oxidation Reaction

Designing cost-effective and highly efficient electrocatalysts for hydrogen evolution reaction (HER) in alkaline media at high current densities is challenging. In this study, we adopted Ru heteroatom doping and an open nanoframe structure to obtain excellent HER catalytic performance. X-ray photoelectron spectroscopy (XPS) visualized the electron transfer due to Ru heteroatom doping in transition metal phosphides, to observe the modulated electronic structure of the Ru-doped CoFeP nanoframe (RCFP/NF). Density functional theory (DFT) calculations and XPS analysis confirmed a d-band center downshift of the RCFP/NF, demonstrating the regulation of the optimal adsorbates (OH*/H*) adsorption free energies. Consequently, RCFP/NF with 4.7 wt % of Ru exhibits a low overpotential of 112 mV, 191 mV, and 219 mV at current densities of 10 mA cm−2, 100 mA cm−2, and 500 mA cm−2, respectively, and an excellent stability for 100 h at a high current density of 100 mA cm−2. This outstanding HER performance at high current density was attributed to the hydrophilic and aerophobic properties of the RCFP/NF catalyst surface that facilitate the exposure of active sites and H2 gas desorption. 

Enhancement of hydrogen evolution activity by tailoring the electronic structure in ruthenium-heteroatom-doped cobalt iron phosphide nanoframes

Enhanced low-temperature behavior of selective catalytic reduction of NOx by CO on Fe-based catalyst with looping oxygen vacancy

Abstract High-performance platinum-group-metal-free alkaline hydrogen oxidation reaction catalysts are essential for the hydroxide exchange membrane fuel cells, which generally require high Pt loadings on the anode. Herein, we report a highly active hydrogen oxidation reaction catalyst, NiCuCr, indicated by the hydroxide exchange membrane fuel cell with a high peak power density of 577 mW cm −2 (18 times as high as the Ni/C anode) and a stability of more than 150 h (a degradation rate slower by 7 times than the Ni/C anode). The spectroscopies demonstrate that the alloy effect from Cu weakens the hydrogen binding, and the surface Cr 2 O 3 species enhance the interfacial water binding. Both effects bring an optimized apparent hydrogen binding energy and thus lead to the high hydrogen oxidation reaction performance of NiCuCr. These results suggest that the apparent hydrogen binding energy determines the hydrogen oxidation reaction performance and that its tuning is beneficial toward high electrocatalytic performance. 

Tuning the apparent hydrogen binding energy to achieve high-performance Ni-based hydrogen oxidation reaction catalyst

Catalytic peroxymonosulfate (PMS) activation processes don’t solely rely on electron transfer from dominant metal centers due to the complicated composition and interface environment of catalysts. Herein the synthesis of a cobalt based metal-organic framework containing polyvanadate [V4O12]4− cluster, Co2(V4O12)(bpy)2 (bpy = 4,4’-bipyridine), is presented. The catalyst demonstrates superior degradation activity toward various micropollutants, with higher highest occupied molecular orbital (HOMO), via nonradical attack. The X-ray absorption spectroscopy and density functional theory (DFT) calculations demonstrate that Co sites act as both PMS trapper and electron donor. In situ spectral characterizations and DFT calculations reveal that the terminal oxygen atoms in the [V4O12]4− electron sponge could interact with the terminal hydrogen atoms in PMS to form hydrogen bonds, promoting the generation of SO5* intermediate via both dynamic pull and direct electron transfer process. Further, Co2(V4O12)(bpy)2 exhibits long-term water purification ability, up to 40 h, towards actual wastewater discharged from an ofloxacin production factory. This work not only presents an efficient catalyst with an electron sponge for water environmental remediation via nonradical pathway, but also provides fundamental insights into the Fenton-like reaction mechanism. Peroxymonosulfate (PMS) activation might not solely rely on electron transfer from dominant metal centers. Here, authors found that the formation of hydrogen bond between PMS and [V4O12] 4− in Co2(V4O12)(bpy)2 catalyst provided extra electron transfer channel for achieving efficient PMS activation.

Multi-channel electron transfer induced by polyvanadate in metal-organic framework for boosted peroxymonosulfate activation

Lattice Oxygen-Induced d-Band Shifting for Enhanced Hydrogen Oxidation Reaction on Nickel

Mild cognitive impairment (MCI) is the early stage of Alzheimer's disease, which is associated with abnormal brain proteins, the recognition of MCI being a challenging task. Recent studies have shown that the performance of MCI identification can be improved by combining protein features captured in Positron Emission Computed Tomography(PET). Nevertheless, there are still great challenges in extracting effective features from the vast amount of information. Most brain networks only considered the unilateral features of nodes or edges, ignored the interactions between them. In response to this problem, our study proposed to combine the quadruple Siamese network and GCN with self-attention pooling(QS-SAGCN) for MCI identification. In detail, we constructed the multiple protein features network(MPN) and higher-order MPN(MPHN) by PET images to promote the MCI identification. Furthermore, a pooling operation with self-attention mechanism was incorporated into GCN(SAGCN), which considered the node characteristics and topology in the graph network to facilitate the acquisition of robust biomarkers, simultaneously. Additionally we combined quadruple Siamese network with SAGCN as classification framework to improve the identification accuracy. Our proposed MCI identification method was evaluated on 230 subjects (including 117 MCI subjects, 113 normal control subjects) with both 18F-AV-1451 PET and 18F-AV-45 PET data from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) database. Experimental results showed that 1) QS-SAGCN enhanced the ability of feature identification, laying the foundation for obtaining more effective biomarkers for MCI patients; 2) The MCI identification accuracy (93.5%) was obtained by combining QS-SAGCN and higher-order network, indicating that the framework had advantages in mental disorders recognition. Finally, through comparison, the accuracy of our proposed MCI recognition method was superior to some of the existing state-of-the-art methods. Overall, the MCI identification method in this study was effective and promising to assist in the diagnosis of MCI in future clinical practice. 

Identification of Mild cognitive impairment based on quadruple GCN model constructed with multiple features from higher-order brain connectivity

Apolipoprotein E 4 Allele (APOE 4) is an important factors in Mild cognitive impairment (MCI) and Alzheimer's disease(AD). It plays a primary role in abnormal modification of aggregated Tau protein-paired helical filaments Tau (PHF-Tau). In this study, 143 subjects with PHF-Tau PET were divided into 2 groups (APOE 4 carriers and noncarriers). The measurements of the PHF-Tau network properties and resilient were calculated for 2 group networks respectively. APOE 4 carriers group showed significant differences in all the network properties in the results. We also found significant differences of betweenness centrality in some brain regions for APOE 4 carriers. Moreover, the APOE 4 carriers showed less resilient to targeted or random node failure. Our results indicated that the effects of APOE 4 may lead to abnormalities of PHF-Tau protein network. These findings may be particularly helpful in uncovering the pathophysiology underlying the cognitive dysfunction in MCI patients.

https://journals.sagepub.com/doi/pdf/10.1177/1533317520971414

A Study on PHF-Tau Network Effected by Apolipoprotein E4:

Proton exchange membrane fuel cells (PEMFCs) have been commercialized, but their elevated costs and inadequate catalytic efficiencies for the oxygen reduction reaction (ORR) have hindered broader use. Metal oxides demonstrate...

Significantly improved stability and water retention for Pt supported on W-doped SnO2 to catalyse the oxygen reduction reaction in proton exchange membrane fuel cells

Patchy Fe-N-C Supported Low-Loading Pt Nanoparticles as a Highly Active Cathode for Proton Exchange Membrane Fuel Cells

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