Appraisal of photoelectrocatalytic oxidation of glucose and production of high value chemicals on nanotube Ti/TiO2 electrode

Selective photoelectrochemical oxidation of glucose to glucaric acid by single atom Pt decorated defective TiO2

Photoelectrochemical reaction is emerging as a powerful approach for biomass conversion. However, it has been rarely explored for glucose conversion into value-added chemicals. Here we develop a photoelectrochemical approach for selective oxidation of glucose to high value-added glucaric acid by using single-atom Pt anchored on defective TiO₂ nanorod arrays as photoanode. The defective structure induced by the oxygen vacancies can modulate the charge carrier dynamics and band structure, simultaneously. With optimized oxygen vacancies, the defective TiO₂ photoanode shows greatly improved charge separation and significantly enhanced selectivity and yield of C₆ products. By decorating single-atom Pt on the defective TiO₂ photoanode, selective oxidation of glucose to glucaric acid can be achieved. In this work, defective TiO₂ with single-atom Pt achieves a photocurrent density of 1.91 mA cm^-2 for glucose oxidation at 0.6 V versus reversible hydrogen electrode, leading to an 84.3 % yield of glucaric acid under simulated sunlight irradiation.

Scaling up Photoelectrocatalytic Reactors: A TiO2 Nanotube-Coated Disc Compound Reactor Effectively Degrades Acetaminophen

Multiple discs coated with hierarchically-organized TiO2 anatase nanotubes served as photoelectrodes in a novel annular photoelectrocatalytic reactor. Electrochemical characterization showed light irradiation enhanced the current response due to photogeneration of charge carriers. The pharmaceutical acetaminophen was used as a representative water micropollutant. The photoelectrocatalysis pseudo-first-order rate constant for acetaminophen was seven orders of magnitude greater than electrocatalytic treatment. Compared against photocatalysis alone, our photoelectrocatalytic reactor at <8 V reduced by two fold, the electric energy per order (EEO; kWh m−3 order−1 for 90% pollutant degradation). Applying a cell potential higher than 8 V detrimentally increased EEO. Acetaminophen was degraded across a range of initial concentrations, but absorbance at higher concentration diminished photon transport, resulting in higher EEO. Extended photoelectrocatalytic reactor operation degraded acetaminophen, which was accompanied by 53% mineralization based upon total organic carbon measurements. This proof of concept for our photoelectrocatalytic reactor demonstrated a strategy to increase photo-active surface area in annular reactors.