Free-Standing Biomass-Derived Hybrid Carbon Electrodes

The method according to anyone of the preceding claims, wherein the architectured polymeric template with a patterned three-dimensional open structure is manufactured by means of additive manufacturing.

The method according to anyone of the preceding claims, wherein the step of providing the architectured polymeric template with a patterned three-dimensional open structure comprises 3D printing the polymeric template with a patterned three-dimensional open structure.

The method according to anyone of the preceding claims, wherein the step of providing the architectured polymeric template with a patterned three-dimensional open structure comprises 3D printing the polymeric template by means of stereolithography (SLA) 3D printing, Digital Light Processing (DLP), projection micro stereolithography (PuSLA), or Two-photon polymerization (2PP).

The method according to anyone of the preceding claims, wherein the architectured polymeric template has an open 3D microlattice pattern.

The method according to anyone of the preceding claims, wherein the architectured polymeric template comprises hollow parts.

The method according to anyone of the preceding claims, wherein the architectured polymeric template has a macroscopic open structure.

The method according to any one of the preceding claims, wherein the architectured polymeric template has a designed macroscopic pattern defined by the placement of individual holes have dimensions in the scale of tenths of milimiters (0.1 mm) to tens of centimeters (10 cm), wherein the placement of said individual holes relative to each other is not arbitrary, and/or is not stochastic, and/or is controlled.

The method according to anyone of the preceding claims, wherein the architectured polymeric template has a microscopic structure.

The method according to any one of the preceding claims, wherein the architectured polymeric template has a designed microscopic pattern defined by the placement of individual holes have dimensions in the scale of tenths of microns (0.1 μm) to tenths of milimiters (0.1 mm), wherein the placement of said individual holes relative to each other is not arbitrary, and/or is not stochastic, and/or is controlled.

The method according to anyone of the preceding claims, wherein the architectured polymeric template comprises a pyrolyzable photopolymer.

The method according to anyone of the preceding claims, wherein the photopolymer is a high-temperature resin.

The method according to anyone of the preceding claims, wherein the photopolymer polymerizes when exposed to actinic radiation.

The method according to anyone of the preceding claims, wherein the photopolymer comprises photopolymerizable groups such as vinyl, allyl, epoxy and/or styrenic groups.

The method according to anyone of the preceding claims, wherein the photopolymer comprises acrylate groups, methacrylate groups, epoxy groups or any combination thereof.

The method according to anyone of the preceding claims, wherein the photopolymer comprises acrylated monomers, epoxy-based monomers and/or methacrylated oligomers.

The method according to any one of the preceding claims, wherein the photopolymer comprises a photoinitiator.

The method according to anyone of the preceding claims, wherein the architectured polymeric template is a pyrolyzable material.

The method according to anyone of the preceding claims, wherein the architectured polymeric template is subjected to a pre-treatment prior to step b., wherein the pre-treatment increases the hydrophilicity of the architectured polymeric template.

The method according to anyone of the preceding claims, wherein the pre-treatment comprises surface coating, plasma treatment, glow discharge, silanization, macromolecule grafting and/or chemical processing of the architectured polymeric template.

The method according to anyone of the preceding claims, wherein the pre-treatment comprises oxygen or air plasma treatment of the architectured polymeric template.

The method according to anyone of the preceding claims, wherein step b. comprises filling the hollow parts of the architectured polymeric template with a homogeneous aqueous solution of a biomass-derived polymer.

The method according to anyone of the preceding claims, wherein step b. comprises cross-linking the biomass-derived polymer to form a hydrogel, thereby obtaining a hydrogel-filled architectured polymeric template.

The method according to anyone of the preceding claims, wherein step b. comprises cross-linking the biomass-derived polymer by gelation by physical cross-linking and/or by a chemical cross-linking to obtain the hydrogel.

The method according to anyone of the preceding claims, wherein the cross-linking is obtained by addition of a cross-linking agent.

The method according to anyone of the preceding claims, wherein cross-linking of the biomass-derived polymer to form a hydrogel comprises spraying the crosslinking agent and/or immersing the architectured polymeric template filled with the biomass-derived polymer in the crosslinking agent.

The method according to anyone of the preceding claims, wherein the architectured polymeric template filled with the biomass-derived polymer is immersed in the crosslinking agent for at least 5 minutes, such as for 5 to 60 minutes, such as for 5 to 30 minutes, such as for 5 to 20 minutes, such as for 5 to 15 minutes, such as for to 20 minutes, such as for about 15 minutes, such as for 12 hours, such as for overnight, such as for 24 hours.

The method according to anyone of the preceding claims, wherein the biomass-derived polymer is a polysaccharide-based polymer.

The method according to anyone of the preceding claims, wherein the biomass-derived polymer is agarose, cellulose, chitosan, gelzan, pectin, lignin or alginate.

The method according to any one of the preceding claims, wherein step b. comprises providing an inorganic compound.

The method according to any one of the preceding claims, wherein the inorganic compound is a water soluble salt of an ion selected from the group consisting of:

• calcium ion, permanganate ion, manganese ion, ruthenium ion, nickel ion, tin ion, iridium ion, iron ion, vanadium ion, cobalt ion, molybdenum ion, zinc ion and any combination thereof.

The method according to any one of the preceding claims, wherein step b. comprises precipitation of the inorganic compound in form of particles within the hydrogel-filled architectured polymeric template.

The method according to any one of the preceding claims, wherein the inorganic compound particles are calcium hydroxide particles.

The method according to any one of the preceding claims, wherein the inorganic compound particles are calcium carbonate particles.

The method according to anyone of the preceding claims, wherein the hydrogel-filled architectured polymeric template is washed with water prior to step c.

The method according to anyone of the preceding claims, wherein step c. comprises drying the hydrogel-filled architectured polymeric template to provide an aerogel-filled template.

The method according to any one of the preceding claims, wherein step c. comprises drying the hydrogel-filled architectured polymeric template using supercritical CO2 drying, freeze drying, ambient drying, microwave drying or a combination thereof.

The method according to anyone of the preceding claims, wherein step c. comprises drying the hydrogel-filled architectured polymeric template using freeze-drying.

The method according to anyone of the preceding claims, wherein step d. comprises pyrolyzing the aerogel-filled architectured polymeric template under a inert atmosphere at 700° C. or more, such as at 750° C. or more, such as at 800° C. or more, such as at 850° C. or more, such at 900° C. or more, such as at 950° C. or more, such as at 1000° C. or more, such as at 1100° C., such as at between 900° C. and 1100° C., for at least 10 seconds, such as for at least 1 minute, such as for at least 10 minutes, such as for at least 30 minutes, such as for at least 60 minutes, such for at least 80 minutes, such as for at least 90 minutes, such as for at least 120 minutes, such as for at least 180 minutes, thereby obtaining a biomass-derived carbon electrode.

The method according to anyone of the preceding claims, wherein the pyrolysis occurs under nitrogen or argon atmosphere, or in vacuum.

The method according to anyone of the preceding claims, wherein the pyrolysis occurs in an oven, a heater, a griller and/or a furnace.

The method according to anyone of the preceding claims, wherein the pyrolyzing occurs in a tube furnace, such as a ceramic tube furnace, or a muffle furnace.

The method according to anyone of the preceding claims, wherein step d. comprises

• a. heating the aerogel-filled architectured polymeric template under inert atmosphere at a temperature between 300° C. and 410° C. for at least 1 minute;
• and
• b. heating the aerogel-filled architectured polymeric template under inert atmosphere at a temperature between 700° C. and 1100° C. for at least 1 minute.

The method according to anyone of the preceding claims, wherein step d. comprises

• a. heating the aerogel-filled architectured polymeric template under an inert atmosphere at 350° C. to 500° C., such as at 400° C. to 450° C., for 30 minutes to 120 minutes, such as for about 1 hour;
• and
• b. heating the aerogel-filled architectured polymeric template under a nitrogen atmosphere at 900° C. to 1100° C. for 30 minutes to 180 minutes, such as for about 2 hour.

The method according to anyone of the preceding claims, further comprising a step of post-activation of the pyrolyzed free-standing biomass-derived carbon electrode after step d.

The method according to any one of the preceding claims, wherein the post-activation is performed by treatment with KOH.

The method according to any one of the preceding claims, wherein the post-activation increases the surface area of the free-standing biomass-derived carbon electrode.

A free-standing hydrogel-filled architectured polymeric template, comprising an architectured polymeric template with a patterned three-dimensional open structure, wherein said architectured polymeric template has a designed macrostructural and/or microstructural architecture, and

• a hydrogel comprising or consisting of a biomass-derived polymer.

A battery comprising a biomass-derived free-standing 3D carbon hybrid electrode according to any one of the preceding claims.

A supercapacitor comprising a biomass-derived free-standing 3D carbon hybrid electrode according to any one of the preceding claims.

A fuel cell comprising a biomass-derived free-standing 3D carbon hybrid electrode according to any one of the preceding claims.

Use of a biomass-derived free-standing 3D carbon hybrid electrode according to any one of the preceding claims for energy storage, energy conversion, electrocatalysis, water and wastewater treatment, and/or CO2 capture.