Untreated Pyrolyzed 3D Bamboo as a Solar Steam Generation Device

In this work, we present a biochar obtained through low-temperature, slow pyrolysis of untreated bamboo, well suited for photothermal applications joining sustainability and consistent heating under sunlight. Bamboo pyrolyzed between 300 and 1000°C was irradiated with simulated sunlight to evaluate the efficiency in sunlight absorption and heat retention. We demonstrate that a pyrolysis temperature as low as 400°C, without any chemical treatment or loading, is optimal to produce an insulating microstructured black absorber, showing the best balance between high light absorption and low thermal dissipation. Indeed, such sample reaches temperatures above 60°C under illumination, well suited to passive heat generation. We demonstrate that the porous channel-like structure of bamboo is preserved during pyrolysis; hence, the bamboo-based monolithic carbon can also act as an interfacial solar steam generator. The latter method is raising increasing interest toward purification of wastewater and desalination; indeed, it has many advantages over traditional methods like reverse osmosis, namely localized heating, low energy consumption, and low carbon emissions. Achieving evaporation rates of up to 1.17 kg h−1 m−2 with this environmentally friendly, abundant, and low-cost source of biomass makes these results particularly interesting, especially for low-income regions affected by freshwater scarcity.