Douman, Samantha FDe Eguilaz, Miren RuizCumba, Loanda R2022-06-222022-06-222021Douman SF, De Eguilaz MR, Cumba LR, Beirne S, Wallace GG, Yue Z, Iwuoha EI and Forster RJ (2021) Electrochemiluminescence at 3D Printed Titanium Electrodes. Front. Chem. 9:662810. doi: 10.3389/fchem.2021.66281022962646doi: 10.3389/fchem.2021.662810http://hdl.handle.net/10566/7530The fabrication and electrochemical properties of a 3D printed titanium electrode array are described. The array comprises 25 round cylinders (0.015 cm radius, 0.3 cm high) that are evenly separated on a 0.48 × 0.48 cm square porous base (total geometric area of 1.32 cm2 ). The electrochemically active surface area consists of fused titanium particles and exhibits a large roughness factor ≈17. In acidic, oxygenated solution, the available potential window is from ∼-0.3 to +1.2 V. The voltammetric response of ferrocyanide is quasi-reversible arising from slow heterogeneous electron transfer due to the presence of a native/oxidatively formed oxide. Unlike other metal electrodes, both [Ru(bpy)3] 1+ and [Ru(bpy)3] 3+ can be created in aqueous solutions which enables electrochemiluminescence to be generated by an annihilation mechanism. Depositing a thin gold layer significantly increases the standard heterogeneous electron transfer rate constant, ko , by a factor of ∼80 to a value of 8.0 ± 0.4 × 10−3 cm s−1 and the voltammetry of ferrocyanide becomes reversible. The titanium and gold coated arrays generate electrochemiluminescence using tri-propyl amine as a co-reactant. However, the intensity of the gold-coated array is between 30 (high scan rate) and 100-fold (slow scan rates) higher at the gold coated arrays. Moreover, while the voltammetry of the luminophore is dominated by semi-infinite linear diffusion, the ECL response is significantly influenced by radial diffusion to the individual microcylinders of the array.enHeterogeneous electron transfer kineticAnnihilation and co-reactant systemVoltammetry3D-electrode arrayElectrochemiluminescenceArticle