Boron-Nitrogen-Edged Biomass-Derived Carbon: A Multifunctional Approach for Colorimetric Detection of HO, Flame Retardancy, and Triboelectric Nanogenerator.

Enhancing the concentration and type of nitrogen (N) dopants within the Sp-carbon domain of carbon recycled from biomass sources is an efficient approach to mimic CNT, GO, and rGO to activate oxidants such as HO, excluding toxic chemicals and limiting reaction steps. However, monitoring the kind and concentration of N species in the Sp-C domain is unlikely with thermal treatments only. A high temperature for graphitization reduces N moieties, leading to low electron density. This inhibits HO adsorption and activation on catalyst surfaces. In this study, coffee waste (CW) is converted into B, N-doped biochar (BNb) using boric acid-assisted pyrolysis (HBOmass = X and carbonization temperature = Y) under N 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 BNb. The optimized BNb exhibits excellent colorimetric sensing performance toward HO 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 Sp domain sizes. Interestingly, B enhances other properties of N-containing CW-derived carbon and introduces self-extinguishing and tribopositive properties. Hence, BNb-coated polyurethane foam shows excellent flame retardancy and energy harvesting performance.