As an alternative to pure lithium-ion, Li, systems, a hybrid magnesium, Mg, and Li battery can potentially combine the high capacity, high voltage, and fast Li intercalation of Li-ion battery cathodes and the high capacity, low cost, and dendrite-free Mg metal anodes. Herein, we report on the use of two-dimensional titanium carbide, TiCT (MXene), as a cathode in hybrid Mg/Li batteries, coupled with a Mg metal anode. Free-standing and flexible TiCT/carbon nanotube composite "paper" delivered ∼100 mAh g at 0.1 C and ∼50 mAh g at 10 C. At 1 C the capacity was maintained for >500 cycles at 80 mAh g. The MoCT MXene also demonstrated good performance as a cathode material in this hybrid battery. Considering the variety of available MXenes, this work opens the door for exploring a new large family of 2D materials with high electrical conductivity and large intercalation capacity as cathodes for hybrid Mg/Li batteries.

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The formation of boron and nitrogen (BN) codoped graphene oxide (GO) from carbon dioxide (CO2) was accomplished using ammonia borane (NH3BH3) as a reducing agent. This graphene-based material was produced in two sequential processes (carbon fixation and pyrolysis) under moderate reaction conditions. One important potential application for the graphene-based material is as catalysts for oxygen reduction reaction (ORR) in fuel cell electrodes. This utilization is supported by the fact that B and N are incorporated into the carbon lattice and the BN insertion improves the electro-catalytic activity for ORR. Electrochemical measurements of BN codoped GO catalysts confirmed the activity for oxygen reduction reaction. The origin of the electro-catalytic activity was elucidated by identifying the insertion of B and N atoms as BCO2 and pyrrolic N in X-ray photoelectron spectroscopy.