Review on candle soot carbon for water splitting applications

Hydrogen energy has proven to be an excellent candidate for replacing conventional energy sources without adverse effects. A cost-effective electrolyzer can effectively generate hydrogen gas by electrochemical water splitting, and it is a greener counterpart to conventional techniques. The development of cost-effective and highly efficient metal electrocatalysts that can outperform state-of-the-art electrocatalysts such as Pt, IrO2, and RuO2 has been proposed to be a favorable alternative to the hydrogen evolution reaction (HER). Carbon is one of the most promising materials for energy applications because of its conductivity, porosity, and abundant availability in nature. Carbon is generated in multiple ways, and appropriate carbon conversion promotes the stability of carbon application and the control of global warming. Recently, researchers have focused on deriving a rigid carbon electrocatalyst from candle soot (CS) and applying it to electrocatalytic reactions. This environmentally benign and cost-effective catalyst synthesis approach has great potential to pave the way for advanced research in this field. A survey of the literature revealed the generation of amorphous carbon, which is evident from the XRD analysis. These carbon nanoparticles arrange to form chain-like structures, with each particle possessing an average diameter ranging from 10-50 nm. These porous layered carbon structures facilitate better water adsorption and triple phase boundaries owing to their greater surface area. During the HER, the CS deposited on nickel foam (NF) achieved an overpotential of-117 mV at-10 mA/cm2. A similar electrochemical activity was observed when Fe-P/CS developed on a flat substrate. A high activity was achieved with the catalyst on a flat substrate because of the high conductivity of carbon and good charge transfer between Fe-P and CS. Similarly, the MoS2/CS/NF catalyst requires only-56 mV to generate-10 mA/cm2. This review compares the development of efficient catalysts, catalyst supports, and doped catalysts utilizing CS for WS applications.