Effect of Transition-Metal Doping in Bismuth Titanate Nanostructures for Enhancing the Photocatalytic Efficiency in the Photodegradation of BPA and Photocatalytic CO₂ Hydrogenation

The present study aims to evaluate the photocatalytic efficiency of transition metal-modified bismuth titanate (BT) for the photocatalytic degradation of a recalcitrant pollutant “bisphenol A” (BPA) and photocatalytic CO2 hydrogenation. Concentration studies of dopants (nickel, Ni; cobalt, Co; and iron, Fe) have been carried out at two distinct concentrations (0.1–0.2 mol %). Transition-metal dopants into the BT lattice modify its electronic structure and charge-carrier dynamics, leading to enhanced photocatalytic efficacy of pristine bismuth titanate. Among the doped samples, Ni-doped BT exhibited the highest photocatalytic efficiency, achieving superior degradation of BPA (approximately 61%) and highest CO2 conversion (32.8%) and reduction to C1 products, selectively carbon monoxide (CO) and methane (CH4), attributed to its optimal band gap and improved electron–hole separation. Moreover, iron doping further led to the proximal degradation of BPA (55%) and 32.1% CO2 conversion, followed by 52% degradation of BPA and 28.8% CO2 conversion by cobalt-doped BT. This current investigation explores the impact of transition-metal modification on BT nanocrystals. Factors such as interfacial charge transfer, band gap adjustments, and surface area played a role in achieving high CO2 conversion and a notable increase in CH4 production compared to pristine BT.