A novel Ni3N/graphene nanocomposite has been synthesized as pseudo supercapacitor electrode material with high capacitance and energy density, due to its unique two-step oxidation/reduction reaction mechanism.

Pursuit of highly active, stable and low-cost electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is the key point for large-scale water splitting. A vanadium nanobelts coating on a nickel foam (V/NF) is proposed as an excellent 3D bifunctional electrode for water electrolysis here, which exhibits high activities with overpotentials of 292 and 176 mV at 10 mA cm(-2) for OER and HER, respectively. When employed as a bifunctional electrocatalyst in an alkaline water electrolyzer, a cell voltage of 1.80 V was required to achieve 20 mA cm(-2) with a slight increase during a 24 h durability test. The existence of the appropriate amount of nitrogen and oxygen elements in the surface region of vanadium nanobelts is regarded to be responsible for the electrocatalytic activity.

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A label-free electrochemical DNA sensor was fabricated by deposition of polyaniline and pristine graphene nanosheet (P/G(ratios)) composites in different mass ratios, DNA probe and bovine serum albumin (BSA) layer by layer on the surface of a glassy carbon electrode (GCE). Electrochemical impedance spectroscopy (EIS) was employed to monitor every step of fabrication of P/G(ratio)-based DNA sensors and to evaluate the detection results in terms of the hybridization of complementary DNA, mutant DNA and non-complementary DNA. The results illustrate that the P/G(ratio)-based DNA sensor could highly efficiently detect complementary DNA from 0.01 pm to 1 μm and discriminate single-nucleotide polymorphisms (SNPs). In the process of detection, double-stranded DNA (dsDNA), resulting from hybridization of a DNA probe, escaping from or remaining on the sensor surface, was monitored by changing the ratio of polyaniline (PANI) to graphene, which was decided by the competition between the electrostatic interaction and Brownian motion.

A highly sensitive and selective tumor cell sensor based on partially oxidized graphene (POG) and folate acid (FA) composite was constructed. The POG was prepared through a modified Hummers method and characterized by means of Raman spectroscopy, X-ray photoelectron spectroscopy, cyclic voltammetry, atomic force microscopy and transmission electron microscopy. The as-prepared POG exhibited the advantages of high electrochemical activity and a good capacity of linking amine derivatives. Using a facile one step reaction, the FA-modified POG was endowed with a more sensitive response to folate-expressing tumor cells than those sensors constructed by the two-step reaction, as well as high selectivity, good reproducibility and long-term stability.