Investigation on copper–nickel co-doped anatase titania nanospheres as an efficient material for photocatalytic and photovoltaic applications

Abstract

In the present study, we have reported the effect of transition metal ions Cu and Ni co-dopants on TiO₂ nanospheres that were synthesized via the sol–gel technique with different molar concentrations of Cu and Ni precursors [[Cu : Ni] 0.075 : 0.025 M (CNT-1), 0.05 : 0.05 M (CNT-2) and 0.025 : 0.075 M (CNT-3)]. The synthesized samples were systematically analyzed via structural, morphological, compositional, optical and electrical properties evaluation for their suitability as photoanodes in DSSCs and photocatalysts in photocatalytic applications. From XRD, all the samples exhibit tetragonal crystal systems with anatase phase and this was in good agreement with micro-Raman analysis. From BET measurement, the specific surface area and pore volume of the sample CNT-2 have a higher value compared to other samples. XPS analysis shows the successful insertion of Cu and Ni into TiO₂ lattice sites. The FESEM images of the synthesized samples were observed to be spherical and this was confirmed via HR-TEM analysis. EDS analysis confirms the presence of elements such as Ti, Cu, Ni and O. From UV-DRS, the optical absorption edge was observed in the visible region and the corresponding band gap values were calculated. The PL emission intensity of CNT-2 shows a lower emission intensity, which reflects the efficiency of the DSSC and photocatalytic applications. From EIS measurements, the charge transfer resistance (R_ct2) and electron relaxation life (τ_e) of CNT-2 are 43.05 Ω and 0.2802 ms showing less recombination and efficient electron injection into CB-TiO₂ and this was supported by the DSSC efficiency of CNT-2 having reached 5.6653%. The photodegradation efficiency of CNT-2 against Rhodamine-B dye is 99.0833% with a lower half-life degradation time and a higher regression coefficient.