Edx system

For the SEM imaging, a 3.0-nm Au/Pd layer was coated on the SSBD spots using a sputtering device (ACE600 Carbon & Sputter Coater). Field emission SEM (Magellan 400) was used to acquire the images at a 5-keV accelerating voltage. EDX mappings were conducted at 10 keV (acquisition time: 60 s) using a Bruker EDX system (Bruker Nano GmbH Berlin) on a FIB-SEM (Helios G4 UX, Thermo Fisher Scientific) platform.

Electrodes
for postmortem studies were washed twice in fresh DMC and then dried
in vacuum. ATR-FT-IR spectra were acquired using a Bruker Lumos II
microscope with an integrated FT-IR spectrometer suited for sample
analysis in attenuated total reflection using a Ge crystal. A resolution
of 4 cm^–1 and 10 scans were set. Raman spectra were
registered using a DILOR LabRam confocal micro-Raman instrument equipped
with a He–Ne laser source at 632.7 nm. Samples were held in
3D-printed sample holders sealed with a cover glass window and nail
polish in order to avoid undesired reactions with air moisture. An
HR-FESEM Zeiss Auriga coupled with a Bruker EDX system was used for
ex situ morphological characterization and elemental mapping of electrodes.

The phytosynthesis of Ag/ZnO@BC was indicated by UV–visible spectroscopy (Genesis 10S UV–VIS spectrophotometer, Thermo scientific). Crystallinity of pristine biochar and Ag/ZnO@BC were determined by XRD (Siemens D-5000) with Cu Kα radiation (λ = 0.154 nm). SEM (model EVO 40, Zeiss) attached to EDX (model Bruker EDX system) were used for the examination of the morphology and analysis of elements. TEM measurements were conducted on a JEOL model 1200EX instrument operated at an accelerating voltage of (80 kV). XPS analysis was collected ESCALAB250Xi (Thermo Scientific, China) spectrometer with a monochromatic Al Kα radiation source (energy 1486.68 eV) at 164 W. FT-IR spectrums were attained over the range of 4000–400 cm⁻¹ using a TENSOR-5, Bruker FTIR Spectrometer. TGA analysis was carried out using Pyris-1, Diamond TG/DTA PerkinElmer. Zeta potentials of synthesized samples were determined using ZetaPALS, Brookhaven, USA to measure their surface charge and stability.