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High cost and vulnerable stability of noble metal catalysts are the main barriers to develop the sustainable clean energy conversion and storage technology. In this work, a novel Co species/N-doped carbon (Co-N-C) derived from ZIF-67 has been designed and successfully prepared by a simple and feasible process. The ORR activities of the obtained Co-N-C with different contents of cobalt species were systematically investigated and clearly elucidated. Notably, the Co-N-C cathode exhibits a high onset-potential −0.12 V (vs. SCE) and long-tern stability in alkaline situation. Furthermore, the self-assembled Zn-air battery and microbial fuel cells (MFCs) devices coupled with Co-N-C cathode also achieve superior open-circuit potentials (Zn-air: 1.40 V, MFC: 0.45 V) and high power densities (Zn-air: 102.3 mW m −2 , MFC: 399.7 ± 10 mW m −2 ). [ABSTRACT FROM AUTHOR]

A simple, portable and recyclable method has been developed for on-site and real-time detection of Hg 2+ and Pb 2+ by naked eyes by using Au nanoclusters-based test paper as the fluorescent sensor. The high specificity of Hg 2+ and Pb 2+ to Au nanoclusters provided excellent selectivity over 15 kinds of other ions. Interestingly, an apparent fluorescent quenching of the test paper was shown when exposed to Hg 2+ , while a significant fluorescent enhancement was observed in the presence of Pb 2+ , which could be attributed to aggregation-induced fluorescence quenching and enhancement. The limit of detection for Hg 2+ and Pb 2+ by naked eyes was 5 μM and 50 μM, respectively. More importantly, the cyclic utilization of the test paper was achieved by immersing the test papers into ethylenediamine tetraacetic acid to recover the fluorescence of the test paper, which contributed to reducing resource consumption. Otherwise, the GSH-AuNCs test paper was competent for a practical application in environmental water samples with strong anti-interference ability. [ABSTRACT FROM AUTHOR]

• A beam-to-column joint with pallet and extended flange plate was proposed and investigated. • Cyclic test results of four full-scale joint specimens were reported and analyzed. • Finite element models of proposed joints were developed and validated for parametric analysis. • Hysteresis behaviors, slipping behaviors, ductility and energy dissipations of the joints were analyzed. • Simplified calculation formulas for the resistance of the joint are proposed. Bolted joints are widely used in beam-to-column joints in structures due to the advantages of fast construction, convenient installation and disassembly, and resource conservation. A bolted joint configuration between L-shaped concrete-filled steel tubular column and H-section beam with lower plate and extended flange plate was proposed, realizing fully-bolted connections between the upper and lower columns, as well as between the beam and the column. Four specimens, with different bolt numbers on the beam flange or different configurations of stiffeners, had been designed and tested under cyclic loads. Finite element models were developed and validated based on the test results, and parametric analysis was performed to analyze the influence of extended flange plate thickness on the mechanical properties of the joints. According to the results, the hysteresis curves of the specimens were plump, and the slippages between the extended flange plate and the beam flange improved the ductility and energy dissipation capacity of the specimens. Increasing bolt number on the beam flange significantly increased the joint resistance and stiffness. The beam vertical stiffeners limited the development of the plastic deformation of the beam flange, thereby reducing the local buckling of the beam section. Based on the experimental and finite element analysis results, simplified calculation formulas and design procedures for the joint are proposed. [ABSTRACT FROM AUTHOR]

High-performance, low-cost, and robust oxygen reduction reaction (ORR) catalysts have played a very crucial role in the development of microbial fuel cells (MFCs). Herein, A novel in-situ Co 3 O 4 nanoparticles (NPs) modified nitrogen-doped graphene with three-dimensional porous structure (3D GN-Co 3 O 4 ) has been successfully synthesized and employed as an efficient ORR catalyst in MFCs. Benefiting from 3D porous architecture feature, highly intrinsic conductivity and synergistic effect between nitrogen-doped graphene and Co 3 O 4 NPs, the 3D GN-Co 3 O 4 as a cathode catalyst in alkaline condition realizes significantly enhanced electrochemical performance and outstanding cycling stability. Furthermore, the self-assembly of MFCs based on the 3D GN-Co 3 O 4 cathode offers a high power density of 578 ± 10 mW m −2 , which is even comparable to the commercial Pt/C. [ABSTRACT FROM AUTHOR]