Morphology and composition were also assessed using scanning transmission electron microscopy with high angle annular dark field (STEM-HAADF; FEI Talos F200X G2) and EDX using samples dried from aqueous suspension on a 300-mesh lacey Cu grid. Inductively coupled plasma optical emission spectroscopy (ICP-OES) and CNH combustion microanalysis were performed by the Microanalysis Service (Yusuf Hamied Department of Chemistry, University of Cambridge). ICP-OES used a Thermo Scientific iCAP 7400 ICP-OES DUO and CNH elemental analysis was performed using an Exeter Analytical, Inc. CE-440 Elemental Analyzer. UV/Vis diffuse reflectance spectroscopy was performed using a Cary 60 UV/Vis spectrophotometer with a Harrick Scientific Video Barrelino diffuse reflectance attachment.