The rubber fruit shell (RFS) activated carbon has been made using KOH as a chemical activating agent with several variations of the impregnation ratio (1:3, 1:4, and 1:5). To ascertain the impact of the impregnation ratio on the attributes of the produced activated carbon, analysis was carried out using thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET) method, X-ray diffraction, and a field emission scanning electron microscope. In the impregnation ratio, 1:5 was carried out as the best result; the value for BET surface area and nitrogen adsorption isotherms were 160 m2/g and 62 cm3/g, where the average pore size diameter was 4.6 nm. Besides, this activated carbon also has around 78.40% carbon. According to the findings of this investigation, the impregnation ratio affects the performance of using KOH as an activator to produce activated carbon from rubber fruit shells. In addition, it could be indicated that the RFS has the potential to be an alternative source of relatively inexpensive activated carbon because the raw materials are available in large quantities.

Hydrogen sulfide (H 2 S) is an offensive-smelling, colorless, and toxic gas that can cause poisoning even in small quantities. In this study, we proposed a sensor that can detect H 2 S with a low composition using SnO 2 and Au nanoparticles as a catalyst. We investigated the structure formed in the thin layer of a sensing material and determined whether it can absorb the tested gas well and produce a high sensing response. We also determined the optimal operating temperature and showed that it has excellent response and recovery times. Pure SnO 2 was synthesized by a simple thermal decomposition method. In the next step, the wet chemical method was used to dissolve the SnO 2 and Au nanoparticles before a viscous liquid compound was deposited onto the electrode by the drop-casting method. The sensor's performance for H 2 S gas detection was tested at low concentrations with four concentrations of Au nanoparticles on SnO 2 -based materials. The results showed that the structure formed in the thin layer is an agglomeration of hollow grains, which allows the gas to be absorbed properly. The result indicated that 40 µl of Au nanoparticles was the optimum concentration for a H 2 S gas sensor, with responses of 65.12% at 0.2 ppm and 87.34% at 1 ppm. The response time was 8 s, whereas the recovery time was 31 s. Moreover, the optimal operating temperature for the reaction was 200 ℃. The findings of this experiment demonstrated that depositing Au-nanoparticle-decorated SnO 2 by the drop-casting method produced a structure with superior gas-sensing performance.