An effective design and fabrication of a more steady structure for high-performance electrodes applications still remains a challenge. Herein, we have designed and fabricated a hierarchical heterostructure of a graphene@polyaniline@ graphene sandwich consisting of hollow polyaniline spheres as the sandwich layer and graphene both as an internal skeleton shell and a cladding layer. The special sandwich configuration not only enlarged the specific surface area but also improved the electrical conductibility. Most importantly, the graphene double shells could prevent the structural breakdown (swelling or shrinkage) of polyaniline. Therefore, as a supercapacitor electrode, the hybrid exhibited excellent performance with a specific capacitance of 682.75 F g −1 at 0.5 A g −1 and a remarkable cycling stability with capacitance retentions of 92.8% after 1000 cycles and even 87.6% after 10,000 cycles, which were better than those of pure polyaniline. In addition, the specific capacitance could reach 217.11 F g −1 at a high current density of 20 A g −1 . Thus, it could be considered as a perspective electrode for the next generation of high-performance supercapacitors.

This article reviews recent developments in droplet microfluidics enabling high-throughput single-cell analysis. Five key aspects in this field are included in this review: (1) prototype demonstration of single-cell encapsulation in microfluidic droplets; (2) technical improvements of single-cell encapsulation in microfluidic droplets; (3) microfluidic droplets enabling single-cell proteomic analysis; (4) microfluidic droplets enabling single-cell genomic analysis; and (5) integrated microfluidic droplet systems enabling single-cell screening. We examine the advantages and limitations of each technique and discuss future research opportunities by focusing on key performances of throughput, multifunctionality, and absolute quantification.

A series of novel surface Ru–H bipyridine complexes-grafted TiO2 nanohybrids were for the first time prepared by a combined procedure of surface organometallic chemistry with post-synthetic ligand exchange for photocatalytic conversion of CO2 to CH4 with H2 as electron and proton donors under visible light irradiation. The selectivity toward CH4 increased to 93.4% by the ligand exchange of 4,4′-dimethyl-2,2′-bipyridine (4,4′-bpy) with the surface cyclopentadienyl (Cp)–RuH complex and the CO2 methanation activity was enhanced by 4.4-fold. An impressive rate of 241.2 μL·g–1·h–1 for CH4 production was achieved over the optimal photocatalyst. The femtosecond transient IR absorption results demonstrated that the hot electrons were fast injected in 0.9 ps from the photoexcited surface 4,4′-bpy–RuH complex into the conduction band of TiO2 nanoparticles to form a charge-separated state with an average lifetime of ca. 50.0 ns responsible for the CO2 methanation. The spectral characterizations indicated clearly that the formation of CO2 •– radicals by single electron reduction of CO2 molecules adsorbed on surface oxygen vacancies of TiO2 nanoparticles was the most critical step for the methanation. Such radical intermediates were inserted into the explored Ru–H bond to generate Ru–OOCH species and finally CH4 and H2O in the presence of H2.

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