Ink-jet printing of NaTaO3 films for photocatalytic H2O and CO2 conversion in seawater

Sodium tantalate (NaTaO3) 3 ) photocatalysts are one of the most promising alternatives for the generation of clean, energetic vectors and solar fuels. One of the main barriers to its massive production is its high cost and complicated synthesis methods as powders. As an alternative, this work sought to provide solutions to manufacture large-area printed films with high throughput rates and minimal waste by ink-jet printing. For this purpose, two formulations of ink were synthesized by changing the concentration of the tantalum (Ta)-precursor to investigate their effect on the physical and photocatalytic properties. The ink-jet printing method promoted the formation of crystalline and porous films with heterogeneous morphology, which effects were more pronounced in samples with higher a Ta concentration in the initial ink. The films were evaluated as photocatalysts in water (H2O) 2 O) and carbon dioxide (CO2) 2 ) reduction to produce hydrogen (H2) 2 ) and formic acid (HCOOH), respectively. The efficiencies of these reactions were significantly promoted by using seawater to take advantage of the dissolved salts, e.g., sodium chloride (NaCl), which could act as hole scavengers promoting higher efficiencies. Additional films were fabricated on stainless steel, which after thermal treatment, promote the in situ formation of junctions with iron oxides NaTaO3/Fe2O3, 3 /Fe 2 O 3 , enhancing the light absorption, the homogeneity, and, consequently, the efficiency of CO2 2 reduction, with productions of up to 25 and 634 mu mol h-1 for H2 2 and HCOOH, respectively. In summary, this work demonstrated the effectiveness of a rapid and lowcost method for fabricating advanced materials with promising activities for renewable energy sources.