Human urine-derived naturally heteroatom doped highly porous carbonaceous material for gas sensing and supercapacitor applications

With the motto of waste is the best basis, we have derived porous carbon material from the most abundant polluting wastes on earth i.e. human urine. Herein, we have fabricated naturally heteroatoms doped and highly porous urine-derived carbon (UC) deposited substrates viz glass and nickel foam via a simple and most cost-effective spray pyrolysis technique and well-characterized using XRD, TEM, FESEM, Raman, XPS, FTIR, BET surface area analyzer etc. standard techniques. The gas-sensing performance of UC film was tested for various volatile gases at room temperature (RT). Among them, methanol (CH3OH) gas has revealed the highest response of 96.8% for 100 ppm concentration with superior response/recovery times (38 s/32 s) at RT. The use of naturally doped carbon with a highly porous surface for energy application is studied by developing the UC fabricated nickel foam electrodes for the supercapacitor. UC electrode exhibited excellent electrochemical performance with a high specific capacitance of 62.5 Fg−1 at 2 Ag−1 for aqueous (6 M KOH) electrolyte in a three-electrode system and the asymmetric device assembled UC//GR (cathode and anode) by this material achieves an energy density of 8.9 Wh/kg and power density of 750 W/kg at 2 Ag−1. Further, the material shows excellent electrochemical stability even after 2,000 cycles. The UC with a highly porous structure gives a high BET surface area of 1238 m2/g, making it a promising material for gas sensor and supercapacitor applications.