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The development of cheap, simple, and green synthetic methods for hierarchically porous nitrogen-doped carbon, especially derived from renewable biomass, such as chitosan, remains a challenging topic. Here, we first synthesized hierarchically porous nitrogen-doped carbon (KIE-8) having graphene-like structure via simple pyrolysis of a chitosan/urea/KOH mixture without any conventional sophisticated treatments, such as freeze-drying, hydrothermal carbonization, and soft or hard templating. On the basis of various analyses of KIE-8, we demonstrated that effect of urea on mesopore formation was insignificant; however, when KOH is used as an activating agent in the presence of urea, a large amount of mesopores can be created along with conventional KOH-derived micropores. In addition, it was revealed that chitosan-derived carbon nanosheets directed by urea are torn into chitosan-derived carbon nanoflakes via KOH activation, and mesopores originate from interstitial voids in aggregates of the carbon nanoflakes, and micropores are derived from in-plane pores in each nanoflake. KIE-8 was used as a catalyst support for formic acid dehydrogenation at room-temperature. Pd­(6 wt %)/KIE-8 catalysts provided excellent catalytic activity (TOF = 280.7 mol H2 mol metal–1 h–1), and we demonstrated that the pore structure and nitrogen structure of KIE-8 are crucial factors to determine the catalytic activity.

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Mesoporous silica and titania supraparticles with controllable pore size, particle size, and macroscopic morphology were readily synthesized by a novel synthetic pathway using meniscus templating on a superhydrophobic surface, which is much simpler than well-known emulsion systems. Moreover, we first report that despite the very large radius of droplet curvature on a millimeter scale, supraparticles kept the round cap morphology due to addition of sucrose as a shape preserver as well as a pore-forming agent. In addition, mesoporous silica and titania supraparticles provided good adsorption performance for Acid Blue 25 and Cr(VI), and were easily separated from the solution by using a scoop net after adsorption tests.

For the application of formic acid as a liquid organic hydrogen carrier, development of efficient catalysts for dehydrogenation of formic acid is a challenging topic, and most studies have so far focused on the composition of metals and supports, the size effect of metal nanoparticles, and surface chemistry of supports. Another influential factor is highly desired to overcome the current limitation of heterogeneous catalysis for formic acid decomposition. Here, we first investigated the effect of support pore structure on formic acid decomposition performance at room temperature by using mesoporous silica materials with different pore structures such as KIE-6, MCM-41, and SBA-15, and achieved the excellent catalytic activity (TOF: 593 h−1) by only controlling the pore structure of mesoporous silica supports. In addition, we demonstrated that 3D interconnected pore structure of mesoporous silica supports is more favorable to the mass transfer than 2D cylindrical mesopore structure, and the better mass transfer provides higher catalytic activity in formic acid decomposition. If the pore morphology of catalytic supports such as 3D wormhole or 2D cylinder is identical, large pore size combined with high pore volume is a crucial factor to achieve high catalytic performance.