Boron-Nitrogen-Edged Biomass-Derived Carbon: A Multifunctional Approach for Colorimetric Detection of H₂O₂, Flame...

Enhancing the concentration and type of nitrogen (N) dopants within the Sp²-carbon domain of carbon recycled from biomass sources is an efficient approach to mimic CNT, GO, and rGO to activate oxidants such as H₂O₂, excluding toxic chemicals and limiting reaction steps. However, monitoring the kind and concentration of N species in the Sp²-C domain is unlikely with thermal treatments only. A high temperature for graphitization reduces N moieties, leading to low electron density. This inhibits H₂O₂ adsorption and activation on catalyst surfaces. In this study, coffee waste (CW) is converted into B, N-doped biochar (B_XNb_Y) using boric acid-assisted pyrolysis (H₃BO₃ mass = X and carbonization temperature = Y) under N₂ to overcome the challenge. The B dopant regulates the concentration and type of N, provides Lewis's acid sites, and converts graphitic-N to pyridine-N in B_XNb_Y. The optimized B₃Nb₉₀₀ exhibits excellent colorimetric sensing performance toward H₂O₂ with a low detection limit (36.9 nM) and high selectivity in the presence of many interferences and milk samples due to high pyridinic-N and Sp² domain sizes. Interestingly, B enhances other properties of N-containing CW-derived carbon and introduces self-extinguishing and tribopositive properties. Hence, B_XNb_Y-coated polyurethane foam shows excellent flame retardancy and energy harvesting performance.