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Achieving large Fermi energy splitting under illumination is critical for improving the performance of photovoltaic devices. In this work, we conducted the energy band structure modulation of MoS2 thin films via MoOx doping scheme to realize its photovoltaic operation on n-type c-Si by magnetron sputtering. It is found that, by capping a MoOx overlayer, the MoS2 electrons density decreased and the Fermi level shifted ~0.4 eV towards valence band, consequently the MoS2 conductive type changing. With this doped MoS2 layer, the built-in electric field of fabricated MoS2/n-Si heterojunction devices greatly improved and exceeded 400 mV owing to the larger interface energy-level differences. Meanwhile, the defects recombination losses reduced benefiting from the holes-selective behavior of O-deficiencies in MoOx, so that the photo-generated carriers extraction process were promoted. As a result, the doped MoS2/n-Si devices showed excellent rectification behavior with rectifying ratio to 105 and ideality of 1.12. The TRPL spectrums corroborated the enhanced carrier transport mechanism at MoS2/n-Si interface by MoOx modulation doping effect. Correspondingly, the significant improvement of doped MoS2/n-Si solar cells performance (Voc of 289 mV, FF of 60.72% and Jsc of 31.25 mA/cm2) was achieved, exhibiting an optimized conversion efficiency of 5.47%. The UPS analysis revealed that the doping mechanism of MoOx/MoS2 stacks lies in energy band overlap and electrons contact transfer between these two materials. This observation of MoOx modulation doping effect on large-area sputtering MoS2 could help in building a better interface carrier transport in photovoltaic and optoelectronic applications of 2D materials.

To develop high-performance hybrid sodium-ion capacitors, B, N co-doped C nanosheets and Bi nanospheres assembled microspheres with petal structure (labelled as Bi NAMPS) are synthesized, which are used as the cathode and the anode, respectively. In sodium-ion half cells, the B, N co-doped C nanosheets show pseudocapacitive behavior, with a stable capacity of 108 mAh g−1 at 0.1 A g−1, superior rate capability (72.9 mAh g−1 at 20 A g−1) and capacity retention of ∼100% after 15000 cycles at 5 A g−1. The Bi NAMPS present battery-type characteristics, with a first reversible capacity of 365 mAh g−1 at 0.2 A g−1, excellent rate capability (343, 338 and 304 mAh g−1 at 10, 20 and 40 A g−1, respectively) and capacity retention of 91% after 7000 cycles at 10 A g−1. Hybrid sodium-ion capacitor constructed by pairing them exhibits an ultrahigh power density of 33 kW kg−1(total), a high energy density of ∼93 Wh kg−1(total) and a long cycle life of 5000 cycles. The improved electrochemical performance of the hybrid sodium-ion capacitor is ascribed to the excellent electrochemical behaviors of the anode and cathode.

The microstructure of MoS2 films is crucial important for its photoelectrical properties, which has significant impact on its application in the field of photovoltaic devices. In this paper, a set of MoS2 thin films with varied thickness was prepared by magnetron sputtering. The influence of the MoS2 microstructure on its optical and electrical properties and, especially, the MoS2/p-Si solar cells photovoltaic performance was investigated in terms of thin films growth. The results reveal that, as the thickness increases, the microstructure of the MoS2 films evolves from amorphous to microcrystalline with the in-plane E2g1 and out-of-plane A1g Raman modes enhancing and the parallel (002) growth orientation increasing. The films electrical conductivity significantly improves owing to the enhanced MoS2 crystallinity. When the thickness is 10 nm, the small ordered MoS2 crystal clusters gradient distribute from the surface to the bulk in the films, contributing to the stress release in the amorphous precursor. Simultaneously, the optical band gap of the MoS2 films shows a maximum of 1.3 eV, due to the less band tail states in the films at the initial phase transition. The optimized optical-electrical properties of the MoS2 films lead to the reducing defects recombination and the enhanced carrier transportation at MoS2/p-Si interface, which promotes the rectification behavior of the pn-junction up to 102. Besides, the significant improvement of the photo-response in MoS2/p-Si heterojunction is obtained, especially in short wavelength range. Correspondingly, the photovoltaic characteristics (Voc, Jsc and FF) of the MoS2/p-Si solar cells increase, and thus an enhancement of the cells conversion efficiency is achieved with 10-nm MoS2 layer.

Influenza viruses have been isolated from dogs in China; however, the extent of influenza infection among dogs is not yet clear. Here, we examined the seroprevalence of avian-origin canine H3N2, pandemic H1N1/09 and human seasonal H3N2 influenza viruses in pet dogs in China during January 2012 to June 2013. The seropositivity rate of canine H3N2, H1N1/09 and human H3N2 were 3.5%, 1.5%, and 1.2%, respectively. Dogs aged 2–5 years were most commonly seropositive to canine H3N2 virus. It is worth noting that two serum samples were positive against both canine H3N2 and H1N1/09 viruses, suggesting the possibility of coinfection with both viruses. Our findings emphasize the necessity for continued surveillance of influenza viruses in dogs in China.

Despite the long-term vaccination programs implemented in China, H9N2 avian influenza viruses (AIVs) continue to persist in chicken populations, even in vaccinated flocks. We previously demonstrated that H9N2 AIV isolated from chickens in China also underwent antigenic drift and evolved into distinct antigenic groups (C, D and E). To understand whether antigenic drift of viruses away from the vaccine strain partially contributed to the circulation of H9N2 AIV in China, we evaluated the protective efficacy of a commercial vaccine against different antigenic groups of H9N2 AIV. Challenge experiments using vaccinated chickens indicated that the vaccine prevented shedding of antigenic group C viruses, but not those of the more recent groups D and E. Vaccinated chickens, even those with vaccine-induced HI titers of 1:1024, shed virus after being infected with A/chicken/Shandong/ZB/2007, a representative virus of antigenic group D. Genetic analysis showed that the representative viruses of antigenic groups D and E possessed greater numbers of amino acid substitutions in the hemagglutinin protein compared to the vaccine strain and the antigenic group C virus, and many of which were located in antigenic sites. Our results indicated that the persistence of H9N2 AIV in China might be due to incomplete vaccine protection, and that the avian influenza vaccine should be regularly evaluated and updated to maintain optimal protection. Furthermore, the avian influenza vaccination policy also needs to be re-assessed, and increased veterinary biosecurity on farms, rather than vaccine application alone, should be implemented to prevent and control avian influenza.

H9N2 influenza viruses have been circulating in China since 1994, but a systematic investigation of H9N2 in northern China has not been undertaken since 2004. Here, using the sequences of 22 viruses we isolated from poultry and pigs in northern China during 2003-2008, in combination with sequences available in a public database, we analyzed the evolution of H9N2 influenza viruses in China from 1994 to 2008. Our findings demonstrated that the H9N2 viruses in China underwent extensive reassortment, and novel genotypes continued to emerge. Among 330 viruses, 54 genotypes were observed including 19 novel genotypes that have not been recognized before, and major genotypes were further divided into five series (BJ/94-, G1-, BG-, F/98- and Aq-series). Different epidemiological and biological features among these series were recognized. The BJ/94- and F/98-series viruses were circulating in both southern and northern China, while the other three series viruses were mainly detected in southern China. BJ/94-series influenza viruses predominated in China before 2000 and were gradually replaced by F/98-series viruses that became the predominant viruses since 2004. At least five antigenic groups could be identified over the study period, during which a significant antigenic drift likely occurred between 2002 and 2003. Animal experiments demonstrated that F/98-series viruses were able to replicate and transmit more effectively in chickens than BJ/94-series viruses. The continuing evolution of H9N2 influenza viruses in China emphasizes the importance of H9N2 influenza virus surveillance throughout this region to aid pandemic prediction and prevention.