Jong Hun Kang

Hummers method has been used for 50 years to prepare graphene oxide (GO) by oxidizing graphite using Mn2O7. In this work, a new angle on Hummers method is described. The oxidation procedure before the addition of water, which has been respected as the main oxidation step of Hummers method, is named step I oxidation, and the widely ignored further oxidation step after the addition of water is named step II oxidation. The chemical and structural evolutions during step II oxidation was demonstrated

The methanol-to-olefins (MTO) process produces high-value-added light olefins from nonpetroleum sources. Acidic zeotypes containing cages bounded by 8-ring (small-pore) windows can effectively catalyze the MTO reaction, since their cages can accommodate the necessary aromatic intermediates that produce the light olefin products that escape. While progress on the mechanisms of the MTO reaction continues, zeotype structure–reaction property relationships have yet to be elucidated. Here, we report

The synthesis of the germanosilicate CIT-13, a molecular sieve that is the first to have a two-dimensional (2D) pore system possessing pores that are bounded by 14- and 10-rings, is accomplished using a family of monoquaternary, benzyl-imidazolium organic structure-directing agents (OSDAs) in aqueous media containing fluoride. CIT-13 is prepared using either hydrogen fluoride (HF) or ammonium fluoride (NH4F). The structure refinement suggests that most of the Ge atoms are located in the d4r (dou

The solvent-free manufacturing process for battery electrodes has gathered increased scientific interest due to its cost reduction, eco-friendliness, and ability to enhance electrode density. Carbon nanotubes (CNTs) are anticipated to improve battery performance, owing to their exceptional electrical conductivity and unique one-dimensional morphology. In this study, we demonstrate that the integration of ozone treatment for CNTs can further enhance the electrochemical performance of high-loading

A series of small-pore zeolites are synthesized and investigated as catalysts for the methanol-to-olefins (MTO) reaction. Small-pore zeolites SSZ-13, SSZ-16, SSZ-27, SSZ-28, SSZ-52, SSZ-98, SSZ-99, SSZ-104, SSZ-105 and an ITQ-3-type material are synthesized, and the results from their use as catalytic materials in the MTO reaction compared to those obtained from SAPO-34. The production of propane that tends to correlate with catalytic material lifetime (higher initial propane yields lead to shor

Polytetrafluoroethylene (PTFE)-based dry process for lithium-ion batteries is gaining attention as a battery manufacturing scheme can be simplified with drastically reducing environmental damage. However, the electrochemical instability of PTFE in a reducing environment has hampered the realization of the high-performance dry-processed anode. In this study, we present a non-electroconductive and highly ionic-conductive polymer coating on graphite to mitigate the electrochemical degradation of th

The 14- and 10-membered ring germanosilicate Ge-CIT-13 (*CTH) is transformed into the 14-membered ring germanosilicate Ge-CIT-5 (CFI). The transformation can occur at room temperature but requires the presence of adsorbed water. The *CTH-to-CFI transformation involves rearrangement of germanium-rich double-4-ring units in *CTH to form double-zigzag chains in CFI. The rate of transformation is dependent on the germanium content of the starting Ge-CIT-13 and the humidity of the transforming atmosp

Abstract The demand for hydrogen production technology to replace fossil fuels and address the global climate crisis has become one of the most urgent tasks in the modern era. Among the promising breakthroughs, electrochemical water splitting using renewable energy sources offers a path to green hydrogen production that is both feasible and economically viable. However, the current state‐of‐the‐art catalysts for the water‐splitting reaction predominantly rely on scarce and costly noble metals, p

Large single crystals of pure-silica STW-type molecular sieves are prepared using 1,2,3,4,5-pentamethylimidazolium (12345PMI) and 2-ethyl-1,3,4-trimethylimidazolium (2E134TMI) as organic structure-directing agents (OSDAs) and α-amino acid additives. The effects of the amount and type of amino acid on the crystallization of pure-silica STW materials are investigated. Room-temperature single-crystal X-ray diffractometry shows that 12345PMI better fits the STW cage than 2E134TMI and is fully consis

Germanium-containing, extra-large pore molecular sieve CIT-13 is synthesized without the use of fluoride. After the removal of occluded organics, CIT-13 obtained from fluoride-free preparation shows significant differences from CIT-13 samples prepared in the presence of fluoride. CIT-13 prepared using a fluoride-free method is able to undergo inverse sigma transformation to yield CIT-14 and transforms into a CIT-5-type germanosilicate much faster than Ge-CIT-13 of similar Si/Ge ratios from a flu

A silicoaluminophosphate molecular sieve, CIT-16P, is synthesized using butane-1,4-bis(quinuclidinium) [(C₇H₁₃N)-(CH₂)₄-(NC₇H₁₃)]²⁺ dihydroxide (DiQ-C₄-(OH)₂) as an organic structure-directing agent (OSDA). Upon the removal of the OSDA, either by thermal treatment in air at temperatures exceeding 490 °C or by extended ozone treatment at 150 °C, CIT-16P transforms to SAPO-17 (ERI topology). The stru