Abstract
The development of highly efficient membranes represents a great opportunity to significantly reduce the environmental impacts of human activities through gas separation and water filtration, and are also very attractive for process intensification when coupled to existing industrial processes. Tubular membranes have higher modularity, better pressure resistance, and they offer easier sealing than their flat counterparts. The ability to deposit thin films on their surface is crucial to optimize their chemical and physical properties. However, the deposition of thin films on tubular membrane supports with conventional vacuum-based deposition techniques is relatively complex, slow and costly. In this work the versatility of spatial atomic layer deposition (SALD) and 3D printing technologies has been combined to design and fabricate a custom SALD manifold for coating tubular substrates. SALD is a scalable deposition technique, offering high-throughput at atmospheric pressure and thus can be advantageously employed to coat tubular membranes, enabling high quality thin films to be deposited at the nanoscale considerably faster than with other conventional techniques. Computational fluid dynamics (CFD) calculations by means of COMSOL Multiphysics have been used to optimize this innovative SALD gas manifold. The proof-of-concept of the new SALD manifold has been validated through successful ZnO thin film depositions performed on tubular Cu foils and porous Al2O3 tubular membrane supports, demonstrating the capability of SALD to achieve high-throughput depositions on non-planar, complex 2 substrates. These results open prospects for the interface engineering of membranes or electrolyzers, where precise coatings of tubular surfaces are needed.