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Functionalized carbon nanomaterials are potential candidates for use as anode materials in potassium-ion batteries (PIBs). The inevitable defect sites in the architectures significantly affect the physicochemical properties of the carbon nanomaterials, thus defect engineering has recently become a vital research area for carbon-based electrodes. However, one of the major issues holding back its further development is the lack of a complete understanding of the effects accounting for the potassium (K) storage of different carbon defects, which have remained elusive. Owing to pressing research demands, the construction strategies, adsorption difficulties, and structure-activity relationships of the carbon defect-involved reaction centers for the K adsorption are systematically summarized using first principles calculations. Carbon defects affect the ability to trap K by affecting the geometry, charge distribution, and conductive behavior of the carbon surface. The results show that carbon doping with pyridinic-N, pyrrolic-N, and P defect sites tend to act as trapping K sites because of electron-deficient sites. However, graphite-N and sulfur doping are less capable of trapping K. In addition, it has been proved using calculations that the defects can inhibit the growth of the K dendrite. Finally, using the molten salt method, we prepared the undoped and nitrogen-doped carbon materials for comparison, verifying the results of the calculation.

Tin (Sn) based anode materials have been regarded as promising alternatives for graphite in lithium ion batteries (LIBs) due to their high theoretical specific capacity and conductivity. However, their practical application is severely restrained by the drastic volume variation during cycling processes. Here we report the preparation of intermetallic SnSb nanodots embedded in carbon nanotube reinforced N-doped carbon nanofibers (SnSb-CNTs@NCNFs) as a free-standing and flexible anode for LIBs. In this unique structure, the SnSb nanodots are well protected by the NCNFs and exhibit greatly reduced volume change. The mechanical strength and conductivity of the nanofabric electrode are further improved by the embedded CNTs. Benefiting from these advantages, the SnSb-CNTs@NCNFs anode delivers a high reversible capacity of 815 mA h g -1 at 100 mA g -1 , a high rate capability (370 mA h g -1 at 5000 mA g -1 ) and a long cycle life (451 mA h g -1 after 1000 cycles at 2000 mA g -1 ). When assembled into flexible pouch cells, the full cells based on SnSb-CNTs@NCNFs anodes also exhibit high flexibility and good lithium storage performances.

N2 fixation is one of the most important chemical reactions in the ecosystem of our planet. However, the industrial Haber-Bosch ammonia synthesis process is restricted by harsh reaction conditions (350-550 °C, 150-350 atm) and undesirable environmental effects (a large amount of CO2 emission). Photocatalytic N2 fixation is promising for achieving sustainable ammonia synthesis under ambient conditions with lower energy input and less environmental issues. However, the known photocatalysts for N2 reduction under mild conditions still face the great challenge of very low energy conversion efficiency. Herein, we report a facile solution-phase method to prepare the heterojunctions based on n-type Bi2MoO6 nanorods and oxygen-vacancy-rich p-type BiOBr nanosheets (Bi2MoO6/OV-BiOBr). Originating from the formation of p-n junctions and suitable bandgap configuration, the Bi2MoO6/OV-BiOBr heterojunctions exhibit effective light utilization and photogenerated electron-hole separation properties. Moreover, it is confirmed that the oxygen vacancies on BiOBr nanosheets are propitious to the adsorption and activation of N2 molecules. Benefiting from these merits, the Bi2MoO6/OV-BiOBr heterojunctions exhibit improved photocatalytic performance for N2 conversion to ammonia without any noble metal co-catalysts and sacrificial reagents under ambient conditions.

Antimony (Sb) based anodes with high conductivity and capability have shown great promise for applications in lithium ion batteries (LIBs). However, they often suffer from poor cycling stability because of the drastic volume variation and structural degradation on undergoing lithiation-delithiation processes. Here we demonstrate a novel Sb-based anode with a free-standing structure realized by uniformly implanting intermetallic compound breithauptite (nickel antimonide, NiSb) nanocrystals into nitrogen-doped carbon nanofibers (NiSb@NCNFs). The discharge/charge behavior of NiSb@NCNFs was systematically investigated by ex situ characterization, which revealed a special "dealloying-lithiation/delithiation-realloying" cycling mechanism. The NiSb nanocrystals possess high lithium storage capacity, and the interconnected network of NCNFs can accommodate the volume variation of encapsulated NiSb nanoparticles, while also providing smooth pathways for charge transport. Compared to other Sb-based anodes, the NiSb@NCNF anode presents exceptional reversible capacity (720 mA h g-1 at a current density of 100 mA g-1) and greatly enhanced cycling life at high rates (510 mA h g-1 after 2000 cycles at 2000 mA g-1). Furthermore, the free-standing NiSb@NCNF anode is free of binders, conductive additives and metal current collectors, exhibiting high flexibility and remarkable performances for the construction of flexible and bendable soft-packed full Li-ion pouch cells.

Solar-driven photocatalytic overall water splitting is regarded as one of the ideal strategies to generate renewable hydrogen energy without the initiation of environmental issues. However, there are still a few remaining challenges to develop wide-light-absorption and stable photocatalysts for the simultaneous production of H2 and O2 in pure water without sacrificial reagents. Herein, we report the design and preparation of Z-scheme TiO2/ZnTe/Au nanocorncob heterojunctions by homogeneously decorating Au nanoparticles onto the surface of core-shell TiO2/ZnTe coaxial nanorods for highly efficient overall water splitting. With the appropriate band structure of TiO2/ZnTe heterojunctions and the surface plasmon resonance enhancement of Au nanoparticles, the well-designed TiO2/ZnTe/Au nanocorncob heterojunctions can synergistically make effective utilization of broad-range solar light illunimation and enhance the separation efficency of electron-hole pairs, as evidenced by UV-Vis absorption and time-resolved photoluminescence spectroscopy. Photoelectrochemical characterization confirms that the water-splitting reaction on TiO2/ZnTe/Au nanocorncobs is mainly carried out via a two-electron/two-electron transfer process with an intermediate product of H2O2. As a result, the TiO2/ZnTe/Au nanocorncob photocatalyst can generate H2 and O2 with a stoichiometric ratio of 2 : 1 under light irradiation without any sacrificial agents, exhibiting a high H2 production rate of 3344.0 μmol g-1 h-1 and a solar-to-hydrogen (STH) efficiency of 0.98%. Moreover, the TiO2/ZnTe/Au nanocorncob heterojunctions show high stability and well-preserved morphological integrity after long-term photocatalytic tests. This study provides a prototype route to produce clean hydrogen energy from only sunlight, pure water, and rationally-designed heterojunction photocatalysts.