Carbon-nitrogen materials as electrodes for reversible hydrogen storage in the proton battery

Porous carbon materials with high surface area and tuneable pore distribution have been proven as suitable materials for the electrochemical storage of hydrogen, without requiring very high pressures or very low temperature being used in commercial methods for storing hydrogen. The presence of nitrogen functional groups on the surface of porous carbon materials offers the direct electrochemical bonding to hydrogen, enhance the storage performance. This report presents the study on the novel synthesis of nitrogen bonded carbon materials, using melamine and terephthalaldehyde as the nitrogen and carbon rich precursors, respectively. The sample synthesis takes place in two batches; unactivated and activated materials. One batch of samples was investigated in an unactivated form and the other with chemical activation by potassium hydroxide (KOH). Further the materials were characterised for morphology, absorption analysis, electrical conductivity, and also investigated by the physical and chemical structural analysis. Nevertheless, the gravimetric maximum reversible atomic hydrogen (H) storage was examined in a proton battery system. The first batch of samples lead to honeycomb sheet-like structure, low BET surface area, broad pore sizes with low pore volume, high nitrogen content, low electrical conductivity, while the activated sample has shown the disordered morphology, very high BET surface area, ultra micro-pores with large pore volume, rich in carbon amount, and optimal electrical conductivity. The results show the H- storage capacity of the unactivated samples increased monotonically with an increase of the melamine (nitrogen) proportion. However, for the activated samples, H storage capacity decreased with an increase of melamine as a precursor. The highest gravimetric reversible H storage capacities of 0.44 wt% were found for the unactivated sample and the H storage of 0.62 wt% for the activated materials. At the end, the future prospects of carbon-nitrogen materials as electrode for H storage are discussed. However, the atomic storage in such materials has been less explored in literature. Nevertheless, the H storage phenomenon in proton battery can surpass many commercially available hydrogen storage methods, which often require either very high pressure or extremely low temperature.