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Fe-N-C represents the most promising non-precious metal catalysts (NPMCs) for the oxygen reduction reaction (ORR) in fuel cells, but often suffers from poor stability in acid due to the dissolution of metal sites and the poor oxidation resistance of carbon substrates. In this work, silicon-doped iron-nitrogen-carbon (Si/Fe-N-C) catalysts were developed by in situ silicon doping and metal-polymer coordination. It was found that Si doping could not only promote the density of Fe-N

Structurally ordered L10-PtM (M = Fe, Co, Ni, etc) intermetallic nanocrystals (iNCs), benefiting from the chemically ordered structure and higher stability, are one of the best electrocatalysts used for PEMFC. However, their practical development is greatly plagued by the challenge that high-temperature annealing (> 700 °C) has to be used for realizing disorder-order phase transition (DOPT) due to the high activation barrier (Ea), which always leads to severe particle sintering, morphology change, and makes it highly challenging for gram-scale preparation of desirable PtM iNCs. Here, we report a general low-melting-point metal induced bond strength weakening strategy to promote DOPT of PtM (M = Ni, Fe, Cu, Zn) alloy catalysts. We demonstrate that the introduction of Sn can reduce DOPT temperature to a record-low temperature (≤ 450 °C), which enables ten-gram-scale preparation of high-performance L10-PtM iNCs. X-ray spectroscopic studies, in-situ electron microscopy and theoretical calculations reveal that the Sn-facilitated DOPT mechanism at record-low temperature involves the weakened bond strength and reduced Ea via Sn doping, the formation and fast diffusion of low coordinated surface free atom, and subsequent L10 nucleation. Most importantly, the 15% Sn-doped L10-PtNi iNCs display outstanding performance in H2-air fuel cells with a high peak power density of 1.45 W cm-2 for Pt alloy catalysts and less than 25% activity loss after 30000 cycles at a quite low cathode Pt loading amount of 0.12 mg¬Pt cm-2, representing as one of the most efficient cathodic electrocatalyst for PEMFCs.

Ni-rich ternary layered oxides represent the most promising cathodes for lithium ion batteries (LIBs) due to their relatively large specific capacities and high energy/power densities. Unfortunately, their inherent chemical instability and surface side reactions during the charge/discharge processes lead to rapid capacity fading and poor cycling life, which seriously restrict their practical applications. Herein, we report a simple dual-modification strategy for preparing LiNi0.6Co0.2Mn0.2O2 (NCM622) cathode materials by Li2SnO3 surface coating and Sn4+ gradient doping. The gradient Sn doping stabilizes the layered structure due to the strong Sn–O covalent bond and relieves the Li+/Ni2+ cation disorder by the partial oxidation of Ni2+ to Ni3+. Besides, the ionic and electronic conductive Li2SnO3 coating serves as a protective layer to eliminate the side reactions with electrolyte/air. In LIB testing, the dual-modified NCM622 cathode with 2% Sn delivers an enhanced cycling performance with 88.31% capacity retention after 100 cycles from 3.0 to 4.5 V at 1C compared to the bare NCM622. Meanwhile, the dual-modified NCM622 shows an improved reversible capacity of 136.2 mA h g−1 at 5C and enhanced electrode kinetics. The dual-modification strategy may enable a new approach to simultaneously relieve the interfacial instability and bulk structure degradation of Ni-rich cathode materials for high energy density LIBs.

The large-scale commercialization of proton-exchange-membrane fuel cells (PEMFCs) is extremely limited by their costly platinum-group metals (PGMs) catalysts, which are used for catalyzing the sluggish oxygen reduction reaction (ORR) kinetics at the cathode. Among the reported PGM-free catalysts so far, metal-nitrogen-carbon (M-N

We report a facile way to prepare sulfur (S) doped Ni4/5Fe1/5-layered double hydroxide (LDH) electrocatalysts for oxygen evolution reaction (OER). The influence of S doping amount on the OER activity of the resulted NiFe-LDHs was studied and the optimal surface S content was ca. 0.43 at%. The developed S-doped NiFe-LDH exhibits excellent OER catalyst activity in 1.0 M KOH with overpotential of only 257 mV at the current density of 10 mA cm-2. Moreover, the catalyst could maintain high activity after 30 h stability test. The high activity of the S-doped NiFe-LDH catalysts may originate from the synergistic effect between S and the Fe sites. This work provides a simple but efficient way to improve the OER performance of transition metal oxides/(oxy)hydroxides.

Atomic ordering engineering has been a promising strategy to improve the catalytic activity and stability of Pt-based alloy catalysts for the oxygen reduction reaction (ORR) for proton exchange membrane fuel cells (PEMFCs). However, the synthesis of shape-controlled ordered nanocrystals, especially in a two-dimensional (2D) architecture, still remains a great challenge. Herein, 2D Pd2Sn nanosheets (NSs) with unique Pd–Sn ordering are developed as efficient ORR electrocatalysts for the first time. The ordered Pd2Sn NSs exhibit a mass activity of 2.5 A mgPd−1 at 0.9 ViR-freevs. the reversible hydrogen electrode and outstanding durability, much superior to that of their disordered counterparts, commercial Pt/C, and most of the reported Pd-based ORR catalysts. The outstanding activity and stability can be ascribed to the unique 2D defect-rich morphology, the thermodynamically stabilized intermetallic structure, and the optimized Pd–O binding due to Sn incorporation.

The development of highly efficient and durable water electrolysis catalysts plays an important role in the large-scale applications of hydrogen energy. In this work, protrusion-rich Cu@NiRu core@shell nanotubes are prepared by a facile wet chemistry method and used for catalyzing hydrogen evolution reaction (HER) in an alkaline environment. The protrusion-like RuNi alloy shells with accessible channels and abundant defects possess a large surface area and can optimize the surface electronic structure through the electron transfer from Ni to Ru. Moreover, the unique 1D hollow structure can effectively stabilize RuNi alloy shell through preventing the aggregation of nanoparticles. The synthesized catalyst can achieve a current density of 10 mA cm

The commercialization of proton exchange membrane fuel cells (PEMFCs) relies on highly active and stable electrocatalysts for oxygen reduction reaction (ORR) in acid media. The most successful catalysts for this reaction are nanostructured Pt-alloy with a Pt-skin. The synthesis of ultrasmall and ordered L10 -PtCo nanoparticle ORR catalysts further doped with a few percent of metals (W, Ga, Zn) is reported. Compared to commercial Pt/C catalyst, the L10 -W-PtCo/C catalyst shows significant improvement in both initial activity and high-temperature stability. The L10 -W-PtCo/C catalyst achieves high activity and stability in the PEMFC after 50 000 voltage cycles at 80 °C, which is superior to the DOE 2020 targets. EXAFS analysis and density functional theory calculations reveal that W doping not only stabilizes the ordered intermetallic structure, but also tunes the Pt-Pt distances in such a way to optimize the binding energy between Pt and O intermediates on the surface.

The oxygen evolution reaction (OER) is involved in various renewable energy systems, such as water-splitting, metal–air batteries and CO2 electroreduction. Ni–Fe layered double hydroxides (LDHs) have been reported as promising OER electrocatalysts in alkaline electrolytes. Herein, we demonstrate that the introduction of elemental selenium (Se) with an optimized phase composition, i.e., monoclinic (m-) or trigonal (t-) Se, could effectively tailor the OER activity of NiFe-LDH. Compared to t-Se doped NiFe-LDH, the presence of hybrid m/t-Se could effectively tune the electronic states of Ni–O and Fe–O sites, promote the generation of OER-active γ-NiOOH, and inhibit Fe-migration during the OER process, thus enhancing the OER performance. The optimized Ni0.8Fe0.2-m/t-Se0.02-LDH catalyst exhibits extraordinarily high OER activity, with an overpotential of 200 mV at 10 mA cm−2, which is superior to those of IrO2 and most of the reported Se-based OER catalysts. The Ni0.8Fe0.2-m/t-Se0.02-LDH catalyst is further implemented as an anode for overall water splitting and demonstrates a low cell voltage of 1.50 V to achieve 10 mA cm−2.

Exploiting platinum-group-metal (PGM)-free electrocatalysts with remarkable activity and stability toward oxygen reduction reaction (ORR) is of significant importance to the large-scale commercialization of proton exchange membrane fuel cells (PEMFCs). Here, a high-performance and anti-Fenton reaction cobalt-nitrogen-carbon (Co-N-C) catalyst is reported via employing double crosslinking (DC) hydrogel strategy, which consists of the chemical crosslinking between acrylic acid (AA) and acrylamide (AM) copolymerization and metal coordinated crosslinking between Co2+ and P(AA-AM) copolymer. The resultant DC hydrogel can benefit the Co2+ dispersion via chelated Co-N/O bonds and relieve metal agglomeration during the subsequent pyrolysis, resulting in the atomically dispersed Co-Nx/C active sites. By optimizing the ratio of AA/AM, the optimal P(AA-AM)(5-1)-Co-N catalyst exhibits a high content of nitrogen doping (12.36 at%) and specific surface area (1397 m2 g-1 ), significantly larger than that of the PAA-Co-N catalyst (10.59 at%/746 m2 g-1 ) derived from single crosslinking (SC) hydrogel. The electrochemical measurements reveal that P(AA-AM)(5-1)-Co-N possesses enhanced ORR activity (half-wave potential (E1/2 ) ≈0.820 V versus the reversible hydrogen electrode (RHE)) and stability (≈4 mV shift in E1/2 after 5000 potential cycles in 0.5 m H2 SO4 at 60 oC) relative to PAA-Co-N, which is higher than most Co-N-C catalysts reported so far.

Ni-rich ternary layered oxides represent the most promising cathodes for lithium ion batteries (LIBs) due to their relatively large specific capacities and high energy/power densities. Unfortunately, their inherent chemical instability and surface side reactions during the charge/discharge processes lead to rapid capacity fading and poor cycling life, which seriously restrict their practical applications. Herein, we report a simple dual-modification strategy for preparing LiNi0.6Co0.2Mn0.2O2 (NCM622) cathode materials by Li2SnO3 surface coating and Sn4+ gradient doping. The gradient Sn doping stabilizes the layered structure due to the strong Sn-O covalent bond and relieves the Li+/Ni2+ cation disorder by the partial oxidation of Ni2+ to Ni3+. Besides, the ionic and electronic conductive Li2SnO3 coating serves as a protective layer to eliminate the side reactions with electrolyte/air. In LIB testing, the dual-modified NCM622 cathode with 2% Sn delivers an enhanced cycling performance with 88.31% capacity retention after 100 cycles from 3.0 to 4.5 V at 1C compared to the bare NCM622. Meanwhile, the dual-modified NCM622 shows an improved reversible capacity of 136.2 mA h g-1 at 5C and enhanced electrode kinetics. The dual-modification strategy may enable a new approach to simultaneously relieve the interfacial instability and bulk structure degradation of Ni-rich cathode materials for high energy density LIBs.

The instinct scaling relations between the adsorption energies of key intermediates during OER lead to large overpotential for water/seawater splitting. Herein, we develop a new strategy to fabricate amorphous nickel-iron phosphides (NiFeP) with controllable morphologies as high-performance catalysts for overall seawater splitting. The ligand effect of P tunes the electronic states of the oxidized NiFe sites, thus breaks the scaling relations for OER and reduce the adsorption energy gap between HO* and HOO* from 3.08 eV to 2.62 eV. The NiFeP nanostructures exhibit extraordinarily low overpotentials of 129 mV for OER and 126 mV for HER at 100 mA cm−2 in simulated alkaline seawater, which outperform the best reported electrocatalysts. They could also be operated at 1.57 V with 100 mA cm−2 in a two-electrode electrolyzer and work for more than 500 h. Our work may provide a universal guidance for the design of highly active seawater splitting electrocatalysts.

Tin selenide (SnSe) has been explored as a promising anode material for sodium ion batteries (SIBs) but its electrochemical performance is strictly limited by the large volume variation during charge/discharge process and relatively low electronic conductivity. In this work, hierarchical Cu doped SnSe nanoclusters were prepared by a cost-efficient and nontoxic method and demonstrated as a high-performance anode for SIBs. Under optimized Cu doping degree (10 wt% Cu), the developed Cu-SnSe anode exhibits excellent rate performance with a high capacity of 330 mAh/g at 20 A/g and outstanding stability with a capacity of 304 mAh/g after 1000 cycles at 5 A/g (0.1–3.0 V vs. Na/Na+). The enhanced electronic conductivity, facilitated sodiation/desodiation process, and relieved volume change during cycling in Cu doped SnSe benefited from Cu doping and the unique hierarchical structure should account for its extraordinary sodiun storage performance.

The commercialization of proton exchange membrane fuel cells (PEMFCs) relies on highly active and stable electrocatalysts for oxygen reduction reaction (ORR) in acid media. The most successful catalysts for this reaction are nanostructured Pt-alloy with a Pt-skin. The synthesis of ultrasmall and ordered L1

The aim of this study was to explore the contribution of microbial community to cellulose degradation during cellulosic wastes composting. Three raw materials with different cellulose content were employed, including rice straws (RS), leaves (L) and mushroom dregs (MD). The cellulose degraded by 92.09%, 56.68% and 40.03% during RS, L and MD composting, respectively, which could be explained by cellulases activity. Besides, each cellulase were only linked to a specific group of bacteria, thus cellulose degradation needed the cooperation of various microorganisms. Ultimately, structural equation models verified that the richness and evenness of microbial community were the primary driving factors of cellulose degradation. The richness symbolized microbial functionality, which was equivalent to the "quality" of microbial species. The evenness symbolized the scope of function, which was equivalent to the "quantity". Therefore, the "quality" and "quantity" of microbial species drove cellulose degradation during RS, L and MD composting.

This study investigated oxytetracycline (OTC) effects on nitrogen (N) transformation and bacterial community diversity during chicken manure composting. The addition of OTC inhibited nitrifying bacteria, resulted in a decrease in the transformation of NH4+-N to NO3−-N during composting, and affected in the order T3 (32.76%) > T2 (28.76%) > T1 (17.02%) > CK. The OTC could act as an inhibitor against core microbial growth, leading to a delay effect during composting. 16S rRNA sequencing was employed for the functional prediction, and results indicated the bacterial community related to N transformation reconstructed under OTC stress. The core microorganisms were changed after OTC addition, with the emergence of Bacillus and Thermobifida, which could inhibit the N transformation by network analysis. Therefore, core microorganisms could be regulated to reduce the negative of OTC impacts on N transformation and thus reduce N loss during composting.