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Catalyzing oxygen reduction reaction (ORR) and accelerating oxygen diffusion are two key challenges for the requirements of the cathode catalysts in the metal‐air batteries. A promising strategy for improving both ORR performance and mass diffusion simultaneously is to build carbon‐based catalysts with ORR‐active chemical dopants and 3D interconnected porosity. Herein, a 3D nanoporous N‐doped carbon with bicontinuous porosity and interconnected open‐pore channels is reported, which is prepared by a polyaniline‐assisted template method. The polyaniline can efficiently inhibit the surface diffusion‐caused template coarsening, achieving a small pore size of 35 nm. The small porous morphology gives rise to a high N‐dopant concentration up to 7.20 at.%, which in turn exhibits a commercial Pt/C‐comparable ORR performance together with satisfied durability in alkaline media. Using these nanoporous carbon catalysts as air electrodes, an all‐solid‐state flexible Al‐air battery is assembled with the measured maximum power density reaching 130.5 mW cm−2, as compared to 106.2 mW cm−2 when the commercial Pt/C standard is used. This study provides an efficient method to synthesize 3D N‐doped carbon with bicontinuous nano‐sized pore channels for wide‐ranging applications in portable and flexible devices. [ABSTRACT FROM AUTHOR]

Keywords: Al-air batteries; nanoporous carbon; N-doped carbon; oxygen reduction reactions; surface diffusion suppression EN Al-air batteries nanoporous carbon N-doped carbon oxygen reduction reactions surface diffusion suppression 1 1 1 09/20/21 20210908 NES 210908 B Nanoporous Carbon b In article number 2103632 Kailong Hu, Hua-jun Qiu, Yoshikazu Ito, and co-workers report a polyaniline-assisted template method to synthesize 3D bicontinuous nanoporous N-doped carbon particles. Al-air batteries, nanoporous carbon, N-doped carbon, oxygen reduction reactions, surface diffusion suppression Inhibiting Surface Diffusion to Synthesize 3D Bicontinuous Nanoporous N-Doped Carbon for Boosting Oxygen Reduction Reaction in Flexible All-Solid-State Al-Air Batteries (Adv. Funct. [Extracted from the article]

• A 3D nanoporous holey graphene with both N and Mo dopants is prepared. • The edge-rich holey graphene facilitates the doping of pyridinic N and single-atom Mo. • The co-doped nanoporous holey graphene is highly active for ORR and OER. Materials co-design of the single-atom catalytic centers and the supports can push the limits of the emerging wearable metal-air batteries. The metal single-atom catalysts are required to be bifunctional with high efficient electrocatalytic activities for both oxygen reduction and evolution reactions (ORR and OER), and preferably non-noble. The supports, on the other hand, in addition to the requirements of being free-standing, flexible and porous, are required to strongly interact with the metal species to prevent their aggregation. However, satisfying these requirements simultaneously is yet challenging. Here, a free-standing 3D nanoporous holey graphene with both N and single-atom Mo dopants is prepared. The nanoholes are created by chemical vapor deposition method on nanoporous NiMo alloy templates with their surface decorated with catalytically inert SiO 2 nanoparticles. The edge-rich graphene induced by the nanoholes facilitates the doping of pyridinic N and single-atom Mo in the fringe near the edges. The resulting N and Mo co-doped nanoporous holey graphene exhibits high bifunctional ORR and OER catalytic activities in alkaline electrolytes. The synergetic effects between N and Mo dopants are also revealed by density functional theory calculations. When incorporated in a solid-state zinc-air battery, the battery is bendable and can be continuously discharged/charged for 88 h with a high power density of 83 mW cm−2. This work provides an efficient route to design metal single atom/cluster doped 3D freestanding nanoporous graphene as flexible electrodes. [ABSTRACT FROM AUTHOR]

Establishing an effective real-time monitoring and early warning system for glacier lake outburst floods (GLOFs) requires a full understanding of their occurrence mechanism. However, the harsh conditions and hard-to-reach locations of these glacial lakes limit detailed fieldwork, making satellite imagery a critical tool for monitoring. Lake Mercbacher, an ice-dammed lake in the central Tian Shan mountain range, poses a significant threat downstream due to its relatively high frequency of outbursts. In this study, we first monitored the daily changes in the lake area before the 2022 Lake Mercbacher outburst. Additionally, based on historical satellite images from 2014 to 2021, we calculated the maximum lake area (MLA) and its changes before the outburst. Furthermore, we extracted the proportion of floating ice and water area during the period. The results show that the lake area of Lake Mercbacher would first increase at a relatively low speed (0.01 km2/day) for about one month, followed by a relatively high-speed increase (0.04 km2/day) until reaching the maximum, which would last for about twenty days. Then, the lake area would decrease slowly until the outburst, which would last five days and is significant for early warning. Moreover, the floating ice and water proportion provides more information about the outburst signals. In 2022, we found that the floating ice area increased rapidly during the early warning stage, especially one day before the outburst, accounting for about 50% of the total lake area. Historical evidence indicates that the MLA shows a decreasing trend, and combining it with the outburst date and climate data, we found that the outburst date shows an obvious advance trend (6 days per decade) since 1902, caused by climate warming. Earlier melting results in an earlier outburst. This study provides essential references for monitoring Lake Mercbacher GLOFs and building an effective early warning system. [ABSTRACT FROM AUTHOR]

[Display omitted] • A general strategy is proposed for the upcycling of residual anodes derived from retired Li-ion batteries into highly valuable electrocatalysts. • The LIB residues are converted into Mn oxide nanoparticles anchored by N and S sites on rGO nanosheets (Mn/NS-rGO). • The binding between Mn and N/S dopants simultaneously optimizes the intermediate adsorption and charge distribution at Mn/rGO interface. • Mn/NS-rGO assembled Al-air battery exhibits an excellent discharge performance under flexible working conditions. Upcycling retired lithium-ion batteries (LIBs) into value-added electrocatalysts represents a promising strategy for tuning the trash into treasure. Herein, an effective approach is reported to convert the LIB anode residues into electrocatalysts that enhance the oxygen reduction reaction (ORR). The residues are utilized for synthesizing reduced graphene oxides (rGO) with Mn nanoparticles anchored by N and S dopants (Mn/NS-rGO). A Pt/C-comparable ORR performance is achieved in alkaline media, with the onset and half-wave potentials of 1.01 and 0.87 V, as well as the excellent durability. Density functional theory (DFT) calculations reveal that Mn sites, coordinating with N and S dopants, simultaneously optimize the intermediate adsorption and charge distribution, which in turn facilitates ORR. The solid-state Al-air batteries are assembled by using Mn/NS-rGO as the cathode catalyst, showing the power density of 103.8 mW cm −2, which successfully charge a cell phone and power LED lights under flexible working conditions. [ABSTRACT FROM AUTHOR]

Layered molybdenum disulphide (MoS2) crystals in combination with graphene create the opportunity for the development of heterostructures with tailored surface and structural properties for energy storage applications. Herein, 2D heterostructures are developed by growing MoS2 on epitaxial and self‐standing nanoporous graphene (NPG) using chemical vapor deposition (CVD). The effect of substrate as well as different CVD growth parameters such as temperature, amount of sulfur and MoO3 precursors, and argon flow on the growth of MoS2 is systematically investigated. Interestingly, various structures of MoS2 such as monolayer triangular islands, spirals, standing sheets, and irregular stacked multilayered MoS2 are successfully developed. The growth mechanism is proposed using different advanced characterization techniques. The formation of a continuous wetting layer with grain boundaries over the surface prior to formation of any other structures is detected. As a proof of principle, MoS2/NPG is employed for the first time as anode material in potassium ion battery. The electrode delivers a specific capacity of 389 mAh g−1 with over 98% stability after 200 cycles. The porous structures clearly facilitate the ion transport which is beneficial for the ion battery. These encouraging results open new opportunities to develop hierarchical heterostructures of 2D‐materials for next‐generation energy storage technologies. [ABSTRACT FROM AUTHOR]

Developing cheap and highly durable non-noble metal catalysts for water electrolysis to sustainably produce hydrogen as alternatives to platinum-based catalysts is essential. Herein, we report graphene-encapsulated NiMo alloys as acid-stable non-noble metal catalyst electrodes. The graphene-encapsulated NiMo cathode showed a highly stable performance in the potential cycling test (10,000 cycles) from 0 to 5.0 A cm−2 and 100 h of durability at a 2.2 V constant cell voltage. A balance between catalytic activity and corrosion in acidic environments was achieved by tuning the number of N-doped graphene layers. Through their application in a full-cell PEM-type water electrolyzer, we verify that noble metal catalysts can be replaced by non-noble metal catalysts. Such cheap acid-stable non-noble metal electrodes have promising practical applications in PEM-type water electrolysis. • Preparation of graphene-encapsulated NiMo cathode catalysts. • Performance validation of non-noble metal catalysts in PEM-type water electrolysis. • For replacement of conventional noble metal catalysts that are expensive. • Various applications involving acidic environments. [ABSTRACT FROM AUTHOR]

Graphane is formed by bonding hydrogen (and deuterium) atoms to carbon atoms in the graphene mesh, with modification from the pure planar sp2 bonding towards an sp3 configuration. Atomic hydrogen (H) and deuterium (D) bonding with C atoms in fully free-standing nano porous graphene (NPG) is achieved, by exploiting low-energy proton (or deuteron) non-destructive irradiation, with unprecedented minimal introduction of defects, as determined by Raman spectroscopy and by the C 1s core level lineshape analysis. Evidence of the H- (or D-) NPG bond formation is obtained by bringing to light the emergence of a H- (or D-) related sp3-distorted component in the C 1s core level, clear fingerprint of H–C (or D–C) covalent bonding. The H (or D) bonding with the C atoms of free-standing graphene reaches more than 1/4 (or 1/3) at% coverage. This non-destructive H-NPG (or D-NPG) chemisorption is very stable at high temperatures up to about 800 K, as monitored by Raman and x-ray photoelectron spectroscopy, with complete healing and restoring of clean graphene above 920 K. The excellent chemical and temperature stability of H- (and D-) NPG opens the way not only towards the formation of semiconducting graphane on large-scale samples, but also to stable graphene functionalisation enabling futuristic applications in advanced detectors for the β-spectrum analysis. [ABSTRACT FROM AUTHOR]

Forest canopy cover (CC) directly and indirectly influences various processes of forest ecosystems. Airborne light detection and ranging (LiDAR) can be used to characterize forest spatial structures and further obtain estimates of forest CC. However, nonreturn laser pulses from targets of interest impact the estimation accuracy of forest CC. The objective of this article was to develop a novel method of estimating the nonreturn laser pulses to improve the estimation accuracy of forest CC using LiDAR data. The improved models for estimating forest CC were developed by introducing the loss ratio of laser pulses and a CC coefficient into the original models. The forest CC reference data were collected and used to validate the forest CC estimates. The results show that the loss ratio for forested areas was much higher than that for open ground areas. The range between the sensor and a target was a crucial factor that caused the loss of returns. The relationship between the range and the loss ratio was nonlinear in both open ground and forested areas. Compared with the original models, the improved models combining the loss ratio and the CC coefficient statistically significantly increased the estimation accuracy of the forest CC. Moreover, the forest CC estimates from the canopy height model (CHM) were more accurate than those from the height normalized point cloud (NPC) data. In addition, the simplified models were more generalized than the other models. This article is novel and has great potential to improve mapping of forest CC. [ABSTRACT FROM AUTHOR]

Abstract: Heavy chemical doping and high electrical conductivity are two key factors for metal‐free graphene electrocatalysts to realize superior catalytic performance toward hydrogen evolution. However, heavy chemical doping usually leads to the reduction of electrical conductivity because the catalytically active dopants give rise to additional electron scattering and hence increased electrical resistance. A hierarchical nanoporous graphene, which is comprised of heavily chemical doped domains and a highly conductive pure graphene substrate, is reported. The hierarchical nanoporous graphene can host a remarkably high concentration of N and S dopants up to 9.0 at % without sacrificing the excellent electrical conductivity of graphene. The combination of heavy chemical doping and high conductivity results in high catalytic activity toward electrochemical hydrogen production. This study has an important implication in developing multi‐functional electrocatalysts by 3D nanoarchitecture design. [ABSTRACT FROM AUTHOR]

Abstract: Heavy chemical doping and high electrical conductivity are two key factors for metal‐free graphene electrocatalysts to realize superior catalytic performance toward hydrogen evolution. However, heavy chemical doping usually leads to the reduction of electrical conductivity because the catalytically active dopants give rise to additional electron scattering and hence increased electrical resistance. A hierarchical nanoporous graphene, which is comprised of heavily chemical doped domains and a highly conductive pure graphene substrate, is reported. The hierarchical nanoporous graphene can host a remarkably high concentration of N and S dopants up to 9.0 at % without sacrificing the excellent electrical conductivity of graphene. The combination of heavy chemical doping and high conductivity results in high catalytic activity toward electrochemical hydrogen production. This study has an important implication in developing multi‐functional electrocatalysts by 3D nanoarchitecture design. [ABSTRACT FROM AUTHOR]

We report on a spatial mapping of the electronic and vibrational structure of three-dimensional (3D) nanoporous graphene architectures, which have a hierarchical pore structure. We demonstrate that the topology, curvature, and pores lead to local changes in the electronic and vibrational structure and in the hybridization states of the carbon atoms (sp 2 vs. sp 3 -like). Nitrogen substitutions in pyrrolic bonding configurations also contribute to local distortions of the planar geometry of graphene. The distortions influence the electronic density of states at the Fermi level by shifting the Dirac cone apex, opening potential avenues for applications of two-dimensional graphene in 3D devices. [ABSTRACT FROM AUTHOR]

In this research, W and Mo were separated and recovered from high-molybdenum synthetic scheelite by leaching with HCl solutions containing H 2 O 2 as the chelating agent. The effects of the leaching parameters, such as temperature, leaching time, HCl concentration and H 2 O 2 concentration, on the recovery of W and Mo were investigated. The results show that W and Mo were effectively extracted at room temperature and low acidity. With a leaching temperature of 30 °C, an L:S ratio of 10:1, an HCl concentration of 1.5 mol/L, an H 2 O 2 concentration of 2.5 mol/L and a leaching time of 40 min, the recovery of W and Mo was 97.7% and 99.4%, respectively. Thermal decomposition was then employed to treat the leaching solution. W was transformed into tungstic acid, whereas Mo remained in solution. At 60 °C, 97.47% of W was precipitated, and the separation factor reached 105. [ABSTRACT FROM AUTHOR]

A suitable way to modify the electronic properties of graphene—while maintaining the exceptional properties associated with its two-dimensional (2D) nature—is its functionalisation. In particular, the incorporation of hydrogen isotopes in graphene is expected to modify its electronic properties leading to an energy gap opening, thereby rendering graphene promising for a widespread of applications. Hence, deuterium (D) adsorption on free-standing graphene was obtained by high-energy electron ionisation of D 2 and ion irradiation of a nanoporous graphene (NPG) sample. This method allows one to reach nearly 50 at.% D upload in graphene, higher than that obtained by other deposition methods so far, towards low-defect and free-standing D-graphane. That evidence was deduced by X-ray photoelectron spectroscopy of the C 1s core level, showing clear evidence of the D-C sp 3 bond, and Raman spectroscopy, pointing to remarkably clean and low-defect production of graphane. Moreover, ultraviolet photoelectron spectroscopy showed the opening of an energy gap in the valence band. Therefore, high-energy electron ionisation and ion irradiation is an outstanding method for obtaining low defect D-NPG with a high D upload, which is very promising for the fabrication of semiconducting graphane on large scale. [ABSTRACT FROM AUTHOR]

Carbon‐based metal‐free catalysts for the hydrogen evolution reaction (HER) are essential for the development of a sustainable hydrogen society. Identification of the active sites in heterogeneous catalysis is key for the rational design of low‐cost and efficient catalysts. Here, by fabricating holey graphene with chemically dopants, the atomic‐level mechanism for accelerating HER by chemical dopants is unveiled, through elemental mapping with atomistic characterizations, scanning electrochemical cell microscopy (SECCM), and density functional theory (DFT) calculations. It is found that the synergetic effects of two important factors—edge structure of graphene and nitrogen/phosphorous codoping—enhance HER activity. SECCM evidences that graphene edges with chemical dopants are electrochemically very active. Indeed, DFT calculation suggests that the pyridinic nitrogen atom could be the catalytically active sites. The HER activity is enhanced due to phosphorus dopants, because phosphorus dopants promote the charge accumulations on the catalytically active nitrogen atoms. These findings pave a path for engineering the edge structure of graphene in graphene‐based catalysts. [ABSTRACT FROM AUTHOR]