Surface Modification of Catalysts via Atomic Layer Deposition for Pollutants Elimination

Combining State of the Art Opensource and Proprietary Machine Learning Technologies to Build a Data Analysis Pipeline for Gasoline Particulate Filters using X-ray Microscopy, Focused Ion Beam-Scanning Electron Microscopy and Transmission Electron Microscopy

The performance of a particulate filter is determined by multi-scale properties that span the macro, meso and atomic scale. Traditionally, the primary role of a GPF is to reduce solid particles and liquid droplets. At the macroscale, transport of gas through a filter’s channels and interconnecting pores act as main transport arteries for catalytically active sites. At the mesoscale, the micropore structure is important for ensuring that there are enough active sites that are accessible for the gas to reach the catalyst nanoparticles. Whereas at the atomic scale, the structure of the catalyst material determines the performance and selectivity within the filter. Understanding all length scales requires a correlative approach but this is often quite difficult to achieve due to the number of software packages a scientist has to deal with. We demonstrate how current state of the art approaches in the field can be combined into a streamlined pipeline to characterise particulate filters by digitally reconstructing the sample, analysing it at high throughput, and eventually used as an input for gas flow simulations and better product design.

Dual promotional effect of CuxO clusters grown with atomic layer deposition on TiO2 for photocatalytic hydrogen production

The promotional effects on photocatalytic hydrogen production of Cu_xO clusters deposited using atomic layer deposition (ALD) on P25 TiO₂ are presented. The structural and surface chemistry study of Cu_xO/TiO₂ samples, along with first principles density functional theory simulations, reveal the strong interaction of ALD deposited Cu_xO with TiO₂, leading to the stabilization of Cu_xO clusters on the surface; it also demonstrated substantial reduction of Ti⁴⁺ to Ti³⁺ on the surface of Cu_xO/TiO₂ samples after Cu_xO ALD. The Cu_xO/TiO₂ photocatalysts showed remarkable improvement in hydrogen productivity, with 11 times greater hydrogen production for the optimum sample compared to unmodified P25. With the combination of the hydrogen production data and characterization of Cu_xO/TiO₂ photocatalysts, we inferred that ALD deposited Cu_xO clusters have a dual promotional effect: increased charge carrier separation and improved light absorption, consistent with known copper promoted TiO₂ photocatalysts and generation of a substantial amount of surface Ti³⁺ which results in self-doping of TiO₂ and improves its photo-activity for hydrogen production. The obtained data were also employed to modify the previously proposed expanding photocatalytic area and overlap model to describe the effect of cocatalyst size and weight loading on photocatalyst activity. Comparing the trend of surface Ti³⁺ content increase and the photocatalytically promoted area, calculated with our model, suggests that the depletion zone formed around the heterojunction of Cu_xO–TiO₂ is the main active area for hydrogen production, and the hydrogen productivity of the photocatalyst depends on the surface coverage by this active area. However, the overlap of these areas suppresses the activity of the photocatalyst.

The depletion zone formed around the Cu_xO clusters is the main photocatalytically active area, and the H₂ production rate depends on surface coverage with this area; however, the overlap of these areas suppresses the photocatalyst activity.