3D printed carbon black-polylactic acid/copper (CB-PLA/Cu) sensor for improved sustainability in monitoring photocatalytic hydrogen peroxide evolution

As the photocatalytic generation of hydrogen peroxide continues to gather increasing interest, there is a significant need to introduce more sustainable methods to monitor the reaction process. The fabrication of low-cost sustainable electrochemical sensors offers an enticing alternative to the current standard methods. This study reports the first use of an electrochemical sensor to monitor such a process. A highly reproducible 3D printed carbon black-polylactic acid/copper sensor with an extremely low fabrication cost of €0.012 was employed to accurately monitor the photocatalytic evolution of hydrogen peroxide. The accuracy was confirmed through strong correlation with a standard fluorescence spectroscopic method. The sensor displayed limit of detection and limit of quantification values of 0.24 µM and 0.79 µM respectively, and a sensitivity of 217 µA mM⁻¹ cm^-2, while also showing strong selectivity towards hydrogen peroxide in the presence of potential interfering species. Moreover, the electrocatalytic surface was capable of ≥ 3x regeneration without significant loss in activity bringing a ≥ 75 % decrease in analysis cost and a significant reduction in potential waste material. This novel approach to monitoring the photocatalytic evolution of hydrogen peroxide presents as a more economical and sustainable alternative to current methods.