The production of various green fuels and valuable chemicals from the electrocatalytic reduction of CO₂, is gaining popularity as a method of CO₂ removal and utilization. Out of the multitude of possible chemicals that can be produced by CO₂ reduction, formate/formic acid shows the most promise, because of its various applications in hydrogen storage, chemical industry and in agriculture. Herein, we report the preparation method for a sustainable electrocatalyst for CO₂ reduction into formate/formic acid. The bismuth based catalysts were prepared from affordable metal-organic-framework precursor called TAL-33. The samples prepared with the optimized carbonization temperature showed high Faradaic efficiency and durability, with very little loss of activity during the stability testing. To prove that the presence of metallic bismuth nanoparticles enhances the electroreduction of CO₂ to formate, theoretical studies were conducted. DFT studies validated that indeed the presence of metallic bismuth sites are linked to the high selectivity of the catalysts.