For the commercialization of hydrogen energy, a technology enabling safe storage and the transport of large amounts of hydrogen is needed. Porous materials are attracting attention as hydrogen storage material; however, their gravimetric hydrogen storage capacity (GHSC) at room temperature (RT) are insufficient for actual use. In an effort to overcome this limitation, we present a N-doped microporous carbon that contains large proportion of micropores with diameters below 1 nm and small amounts of N elements imparted by the nitrogen plasma treatment. The N-doped microporous carbon exhibits the highest total GHSC (1.59 wt%) at RT, and we compare the hydrogen storage capacities of our sample with those of metal alloys, showing their advantages and disadvantages as hydrogen storage materials.

Hydrogen energy is promising renewable energy and specifically, hydrogen storage is a bottleneck to commercializing hydrogen energy. Researchers have relied on the synthesis of porous materials in physisorption and lowering the H₂ binding energy of hydride materials in chemisorption, all of which have been conducted in a similar manner respectively. However, the development of hydrogen storage materials applicable to onboard system isn’t found yet. Hence, we examined the phenomenon of eccentric H₂ storage in carbon nanopores with sub-1 nm diameters reported earlier, finding a lack of deep research on the fundamentals of this phenomenon. We formulate a hypothesis of H₂ storage by intrinsic EMF (IEMF) interaction and firstly discover that in contrast to general intuition, the neutral carbon nanopore forms a significant IEMF even without an external EMF. Moreover, we confirm the difference of IEMF inside the nanopore from that outside the nanopore due to the overlap between the graphene layers and demonstrate that the resultant IEMF inside the nanopore governs the H₂ storage in the carbon nanopore. This result will shed light on all the other areas related to abnormal phenomena in nanopores with sub-1 nm diameters.

Hydrogen is expected to overcome energy resource depletion because it is the most abundant element in the universe and because an ideal hydrogen energy cycle has the potential to exploit energy infinitely. Conventionally, hydrogen storage utilizes compression under high pressure (350-700 bar) into a tank and liquefaction in the cryotemperature regime (20 K). To mitigate the impractical operating conditions researchers have conducted adsorption-dependent research to increase the specific surface area (SSA) in physisorption and to decrease the H₂ binding energy in chemisorption. Nevertheless, these strategies are still unlikely to reach the required the U.S. Department of Energy (DOE) targets. To this end, researchers have tried to find hydrogen storage material to fit the H₂ binding energy between the physisorption region and chemisorption region. Previous governing parameters, the SSA, and the H₂ binding energy show no correlation to gravimetric H₂ storage capacity (GHSC). In addition, no correlation between the H₂ densification index (HDI) and the H₂ binding energy is found as well, which means the latter cannot describe the H₂-adsorbent interaction thoroughly. The several notable findings presented here suggest that the development of high-performance H₂ storage materials can be realized through the optimal modulation of an underlying parameter that dominates the H₂-adsorbent interaction. This paper highlights the necessity of research on what the underlying parameter that dominates the H₂-adsorbent interaction is and on how it affects GHSC to develop H₂ storage materials that meet the DOE targets.

Conductive microspheres are prepared using two different shaped conductive fillers, carbon nanotubes (CNTs) and Au nanoparticles (AuNPs), by a dry particle coating (DPC) process and a self-assembly method. CNTs, which are  one-dimensional conductive fillers, facilitate the  formation of  conducting pathways so  that the  zero- dimensional AuNP content can be significantly reduced to obtain electrical percolation from the conductive microspheres. Two fabrication methods are investigated: (1) the self-assembly of AuNPs followed by the DPC of the CNTs on polystyrene (PS) microspheres (t-PS/AuNP/CNT) and (2) the DPC of the CNTs followed by the self- assembly of AuNPs (PS/t-CNT/AuNP). In both cases, the electrical percolation of the conductive microspheres is achieved using a significantly lower amount of AuNPs (1 wt%), which is 17 times lower than that of samples prepared using only AuNPs (17 wt%). Interestingly, each sample exhibits distinct conducting behaviors with different amounts of AuNPs owing to the different hybridization structures of AuNPs and CNTs.