Porous Wood Monoliths Decorated with Platinum Nano-Urchins as Catalysts for Underwater Micro-Vehicle Propulsion via H₂O₂ Decomposition

Porous carbon is becoming an important and promising high-surface-area scaffold material for various energy-based applications including catalysis. Here we demonstrate the growth of urchin-like platinum nanoparticles (PtNPs) on carbon monoliths derived from basswood that work as catalysts for micro underwater vehicle (MUV) propulsion via H 2 O 2 decomposition. The carbon monoliths were constructed of natural basswood that was carbonized in argon (Ar) and subjected to a subsequent CO 2 activation process that rendered the material into a hardened 3D porous activated carbonized wood (ACW) with inner channel voids measuring 10–70 μm in diameter. The PtNP nano-urchins (500 nm or less in total diameter, with individual nanospikes measuring 3–5 nm in diameter) form on the ACW via a facile electroless and template-free chemical deposition approach that utilizes the reduction of chloroplatinic acid. The developed PtNP–ACW hybrid material exhibited higher catalytic efficiency as compared to previously reported platinum (Pt) catalysts with a low activation energy of 18.9 ± 2.5 kJ mol –1 for H 2 O 2 decomposition. The catalyst also proved useful in an important energy application by its ability to rapidly decompose H 2 O 2 fuel and generate O 2 gas for propulsion of a 3D printed MUV prototype. The PtNP–ACW catalysts weighing only 0.14 g generated a propulsion thrust of 230 mN, which is sufficient to power MUVs. The natural wood derived carbon scaffolds significantly reduce the overall cost as compared to other carbon-based catalysts such as carbon nanotubes or graphene without reducing catalytic efficiency. Hence, such catalysts act as a stepping stone for potential low cost and sustainable power for burst thrust operation of MUVs.