Rational design of efficient and durable bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrocatalysts is critical for rechargeable metal-air batteries. Here, we developed a facile strategy for fabricating three-dimensional phosphorus and sulfur codoped carbon nitride sponges sandwiched with carbon nanocrystals (P,S-CNS). These materials exhibited high surface area and superior ORR and OER bifunctional catalytic activities than those of Pt/C and RuO, respectively, concerning its limiting current density and onset potential. Further, we tested the suitability and durability of P,S-CNS as the oxygen cathode for primary and rechargeable Zn-air batteries. The resulting primary Zn-air battery exhibited a high open-circuit voltage of 1.51 V, a high discharge peak power density of 198 mW cm, a specific capacity of 830 mA h g, and better durability for 210 h after mechanical recharging. An extraordinary small charge-discharge voltage polarization (∼0.80 V at 25 mA cm), superior reversibility, and stability exceeding prolonged charge-discharge cycles have been attained in rechargeable Zn-air batteries with a three-electrode system. The origin of the electrocatalytic activity of P,S-CNS was elucidated by density functional theory analysis for both oxygen reactions. This work stimulates an innovative prospect for the enrichment of rechargeable Zn-air battery viable for commercial applications such as armamentaria, smart electronics, and electric vehicles.

The hydrogen evolution reaction (HER) is one of the key steps in clean and efficient energy conversion techniques; however, the mass production of current HER devices is hampered by several shortcomings, which include kinetically sluggish processes, stability, and the use of expensive catalysts. In this work we report the facile synthesis of metal‐free hybrids by integrating graphitic carbon nitride (g‐C3N4) with nitrogen‐ and phosphorus‐doped nanoporous graphene sheets. A phosphorus‐doped metal‐free hybrid electrocatalyst (g‐C3N4@P‐pGr) displayed excellent HER performance with an overpotential of −0.34 V, high exchange current density of 3.33×10−6 A cm−2, onset potential of 0.076 V, Tafel slope of 90 mV dec−1, Gibbs free energy of −0.16 eV, and long‐term durability comparable to that of well‐developed metal catalysts. Tafel slope analysis suggests that the Volmer–Tafel mechanism is the most favorable HER kinetics for these metal‐free hybrids. The extraordinary HER performance stems from a strong synergistic effect between the highly exposed active sites generated by the introduction of in‐plane pores into graphene and the coupling of g‐C3N4.

The hydrogen evolution reaction (HER) via water splitting requires the development of advanced and inexpensive electrocatalysts to replace expensive platinum (Pt)-based catalysts. The scalable hydrothermal synthesis of SnS on N-reduced graphene (N-rGr) sheets is presented for the first time, which is used as a highly-active electrocatalyst with long-term stability in acidic, neutral, and alkaline media. This hybrid catalyst reveals a low overpotential of -125 mV, Tafel slope of 38 mV dec(-1), exchange current density of 6.23 mA cm(-2), onset potential of 59 mV, and long-term durability.

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BackgroundHuman Papillomavirus (HPV) is well known pathogen that can cause benign and malignant tumors in humans, yet there is very little information regarding HPV types prevalent in Pakistan.MethodsA total of 92 cervical secretions were collected from suspected married female patients and used for DNA isolation using a novel isolation method. The samples were tested through Polymerase Chain Reaction (PCR) using already reported primers MY09/MY11, GP5/GP6, GP5+/GP6+, CP65/CP70, CP66/CP69 and SPF1/SPF2 and with those developed in this study including HRT1 and HRT2 primer sets for typing HPV types and HACTB primer set for human beta actin gene as internal positive control. Sequencing and phylogenetic analyses were performed for two isolates to determine circulating HPV types.ResultsPCR with HRT1 and HRT2 indicated 2 (2.17 %) patients were positive for HPV type- 16 while 1 (1.08 %) with HPV type 18. Sequencing and phylogenetic analysis of isolates confirmed HPV type-16 in genus alpha 9 which have 99 % homology with already reported HPV from Japan and Costa Rica.ConclusionThis is the first report of HPV type-16 genus alpha 9 in Pakistan and the reported assay and sequence data will serve as valuable tools in further epidemiological studies for HPV surveillance to improve public health, especially of females in Pakistan.