Mesoporous carbons synthesized via a soft-templating approach have attracted much attention due to their easy synthesis and facile control over the derived pore structure. In analogy to soft-templating approaches for mesoporous metal oxides, their synthesis is based on a sequence of forming supramolecular arrangements of precursor molecules with the soft templates, stabilization of the precursor framework by polymerization and finally the removal of the templates. Using micelles of amphiphilic block-copolymers as templates, facile control over the morphology and size of mesopores can be achieved by e.g. controlling size, composition, and concentration of the template polymers or composition and degree of polymerization of the precursor. Moreover, soft templating approaches can be extended to obtain also carbon materials with hierarchical meso- and macroporosity. The additional macroporosity either can result from templating by polymer latex or is induced via macrophase separation. In this review, we describe recent progress and examples in the synthesis and application of mesoporous carbon materials based on soft-templating approaches. Moreover, we reiterate fundamental principles of self-aggregation, highlight proposed synthesis mechanisms and present means of controlling pore size, also in hierarchical meso–macroporous carbon materials.

Troublesome aquatic weed, water hyacinth (Eichhornia crassipes) was converted into solid and liquid fractions via green and energy-saving hydrothermal carbonization (HTC). The solid product, hydrochar, was employed as a precursor to prepare magnetic carbon materials by simple activation and magnetization using KOH and Fe³⁺ ions, respectively. The obtained magnetic adsorbent possessed good magnetic properties and presented outstanding capacities to adsorb methylene blue (524.20 mg g⁻¹), methyl orange (425.15 mg g⁻¹) and tetracycline (294.24 mg g⁻¹) with rapid adsorption kinetics even at high concentrations (up to 500 mg L⁻¹), attributed to high specific surface area and mesopore porosity. Besides the solid hydrochar, the water-soluble liquid product was used to fabricate carbon-based supercapacitors through facile KOH activation with a considerably lower KOH amount in comparison to conventional activation. The supercapacitor electrode made from activated liquid product possessed an extremely high specific surface area of 2545 cm² g⁻¹ and showed excellent specific capacitance (100 F g⁻¹ or 50 F cm⁻³ at 1 A g⁻¹) and good retention of capacitance (92% even after 10 000 cycles). This work demonstrated that both solid and liquid HTC fractions from this bio-waste can serve as effective sources to prepare functional carbon materials, making this approach a sustainable zero-waste biomass conversion process.