Atomic Layer Deposition as a General Method Turns any 3D-Printed Electrode into a Desired Catalyst: Case Study in Photoelectrochemisty

3D-printing technologies have begun to revolutionize many manufacturing processes, however, there are still significant limitations that are yet to be overcome. In particular, the material from which the products are fabricated is limited by the 3D-printing material precursor. Particularly, for photoelectrochemical (PEC) energy applications, the as-printed electrodes can be used as is, or modified by postfabrication processes, e.g., electrochemical deposition or anodization, to create active layers on the 3D-printed electrodes. However, the as-printed electrodes are relatively inert for various PEC energy applications, and the aforementioned postfabrication processing techniques do not offer layer conformity or control at the Ångström/nano level. Herein, for the first time, atomic layer deposition (ALD) is utilized in conjunction with metal 3D-printing to create active electrodes. To illustrate the proof-of-concept, TiO₂ is deposited by ALD onto stainless steel 3D-printed electrodes and subsequently investigated as a photoanode for PEC water oxidation. Furthermore, by tuning the TiO₂ thickness by ALD, the activity can be optimized. By combining 3D-printing and ALD, instead of other metal deposition techniques, i.e., sputtering, rapid prototyping of electrodes with controllable thickness of the desired material onto an as-printed electrodes with any porosity can be achieved that can benefit a multitude of energy applications.