XRD — Sampling between 2θ of 20–90 with Cu K alpha X-rays.

HPLC — Degradation experiments used 1 mL samples taken every 15 or 30 minutes. Analysis was performed on a Thermo Scientific Ultimate 3000 liquid chromatograph with a UV detector. CBZ analysis used a Thermo Scientific Acclaim 120 C18 column (3.0 × 75.0 mm, particle size 3.0 µm) and a Thermo Scientific Acclaim 120 C18 guard column (R) 120 C18 (3.0 × 10.0 mm, particle size 5.0 µm). The mobile phase was made up using 5.0 mM phosphoric acid and acetonitrile 70:30 (v:v) with a flow rate of 0.8 mL min⁻¹, injection volume of 20 µL and detection wavelength of 285 nm.

ICPMS — All samples, standards and blanks, were spiked with internal standard elements Be, In, and Re. The Zn concentration was calibrated using six synthetic standards prepared from a 1000 ppm Inorganic Ventures (VA, USA).

XPS — Kratos Axis UPRA using monochromated Al kα (1486.69 e ) X-rays at 15 mA emission and 12 kV HT (180W) and a spot size/analysis area of 700 × 300 µm and a He(I) UV lamp running at 20 mA emission. The instrument was calibrated to gold metal Au 4f (83.95 eV) and dispersion adjusted gave a BE of 932.6 eV for the Cu 2p3/2 line of metallic copper. Ag 3d5/2 line FWHM at 10 eV pass energy was 0.544 e. Source resolution for monochromatic Al Kα X-rays is ~0.3 eV. The instrumental resolution was determined to be 0.29 eV at 10 eV pass energy using the Fermi edge of the valence band for metallic silver. Resolution with charge compensation system on <1.33 eV FWHM on PTFE. High resolution spectra were obtained using a pass energy of 20 eV, step size of 0.1 eV and sweep time of 60s, resulting in a line width of 0.696 eV for Au 4f7/2. Survey spectra were obtained using a pass energy of 160 eV. Charge neutralisation was achieved using an electron flood gun with filament current = 0.4 A, charge balance = 2  , filament bias = 4.2. Successful neutralisation was adjudged by analysing the C 1s region wherein a sharp peak with no lower BE structure was obtained. Spectra have been charge-corrected to the main line of the carbon 1s spectrum (adventitious carbon) set to 284.8 eV. 

All data was recorded at a base pressure of below 9 x 10-9 Torr and a room temperature of 294 K. Data was analysed using CasaXPS v2.3.19PR1.0. Peaks were fit with a Shirley background prior to component analysis.