Reduction of carbon dioxide into value added chemicals and fuel

Electrochemical CO2 reduction reaction (CO2RR) systems are a viable strategy to mitigate the rising CO2 level in the atmosphere. If powered by photovoltaic cells, these systems also shed light onto the storage as well as the distribution of the intermittent and diffusive solar energy. At present, precious metals such as Au and Pd are regarded as benchmark catalysts for CO2RR to generate CO, while their high-cost would inevitably impair the potential of large-scale implementation. In addition to generating CO, the conversion of CO2 into liquid products such as formate, ethanol and methanol are also of extensive interest as the liquid phase products can be readily stored, transported and utilized within existing infrastructure. However, current benchmarked catalysts for liquid production suffer from poor product selectivity and stability issues meanwhile requiring high applied overpotentials. The aim of this research project is to elucidate the abovementioned barriers by designing scalable catalysts for the conversion of CO2 to value added chemicals. In this regard, a range of novel CO2RR catalysts are developed using tailor-made fabrication techniques: (i) three-dimensional porous silver foam (AgFoam) to improve mass transport, (ii) defect-rich nitrogen removed mesoporous carbon catalyst (NRMC) as a metal-free alternative for CO generation, (iii) surface engineered tin foil (An-Sn) to expose more SnOx/Sn interfaces, (iv) mesoporous tin oxide (m-SnO2) with high oxygen vacancy defects, and (v) heterostructured Cu sandwich electrode that maintained the presence of Cu2+/Cu+ interfaces. The catalytic properties of the above-mentioned catalysts were then investigated with electrochemical techniques namely, cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry (i-t), impedance spectroscopy (EIS), etc. and the products were detected with the aid of gas chromatograph (GC) and nuclear magnetic resonance (NMR). The physiochemical properties of the catalysts were also determined with the aid of a range of characterization techniques namely, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman spectroscopy, Electron Paramagnetic Resonance (EPR), Brunauer-Emmet-Teller (BET) and Focused Ion Beam TEM (FIB-TEM). Density Functional Theory (DFT) calculations carried out were used to confirm the experimental findings. Overall, a clear relationship between the catalytic activity and physiochemical properties of the catalysts were demonstrated and new active sites for CO2RR were revealed