This thesis focuses on the synthesis of nanocatalysts for the electroreduction of CO¬2 to useful fuels such as formic acid, methanol, methane and carbon monoxide. Copper-based materials were synthesised via a continuous hydrothermal flow synthesis process (CHFS). This method involved mixing pressurised precursor solutions with supercritical water to rapidly form ultra-fine nanocatalysts. CuO synthesis was investigated by varying experimental parameters, such as mixer types, temperature, pH, metal salt precursor and H¬2O¬2. Particle size was modulated by controlling these parameters and sub-15 nm particle sizes were possible. This has not been previously observed or reported in the literature in flow synthesis for CuO. The as-prepared CuO nanoparticles were formulated into Nafion based inks. The influence of the Nafion fraction on the Faradaic efficiencies and overpotential was explored. The highest Faradaic efficiency for formic acid production (61%) was observed with the optimum Nafion fraction. Insights into the significant increase in the Faradaic efficiency with the optimum Nafion content was elucidated with electrochemical impedance spectroscopy (EIS). Ni doped CuO synthesised via CHFS, was reported here for the first time, where higher inclusion of Ni was possible compared to co-precipitation. The Ni doped CuO samples were evaluated for their electrocatalytic properties and showed higher Faradaic efficiency at lower overpotential (<1.2 V) and below 11 at % Ni, compared to the undoped CuO. The catalysts were evaluated by EIS, Tafel analysis and structural characterisation. Rotating Ring Disk Electrode (RRDE), a hydrodynamic technique, was validated as a high-throughput tool to screen catalysts prior to bulk electrolysis. The Pt ring was successfully used to electrochemically detect formic acid, as it was formed in situ on copper-based catalysts. This was confirmed by conducting product calibration and understanding the oxidation behaviour on Pt as a function of rotation and scan rate
