***Combining Nickel- and Zinc-Porphyrin Sites via Covalent Organic Frameworks for Electrochemical CO2 Reduction*** 
Authors: Hugo Veldhuizen,(a,b) Maryam Abdinejad,(c) Pieter J. Gilissen,(d) Thomas Burdyny,(c) Frans D. Tichelaar,(e) Sybrand van der Zwaag,(b) and Monique van der Veen(a)
(a) Catalysis Engineering, Faculty of Applied Sciences, Delft
(b) Aerospace Structures and Materials, Faculty of Aerospace Engineering, Delft 
(c) Materials for Energy Conversion and Storage, Faculty of Applied Sciences, Delft
(d) Molecular Nanotechnology, Institute for Molecules and Materials, Radboud Universiteit, Nijmegen
(e) Kavli Institute of Nanoscience, Quantum Nanoscience, Physics building, Technische Universiteit Delft

Corresponding authors: 
T. Burdyny
Contact Information: T.E.Burdyny@tudelft.nl
Delft University of Technology - Faculty of Applied Sciences
Building 58
Van der Maasweg 9
2629HZ Delft
The Netherlands
M. A. Van der Veen
Contact Information: M.A.vanderVeen@tudelft.nl
Delft University of Technology - Faculty of Applied Sciences
Building 58, room E2.180
Van der Maasweg 9
2629HZ Delft
The Netherlands

***General Introduction***
This dataset contains characterization data concerning 5 different Covalent Organic Frameworks (COFs) as part of Hugo Veldhuizen's PhD Thesis project (2018 - 2023).
It is being made public both to act as supplementary data for publications and the PhD 
thesis of Hugo Veldhuizen and in order for other researchers to use this data in their own 
work.
The data in this data set was collected in the Delft University of Technology:
1. Delft Aerospace Structures and Materials Laboratory (chemical and physical lab; Faculty of Aerospace Engineering).
2. NMR, Electrocatalytic data (Faculty of Applied Sciences) 
3. TEM (Kavli Institute)
between July 2021 and December 2022.

***Purpose of this research***
The purpose of these experiments was to investigate the structure and catalytic activity of COFs bearing Ni- and Zn-porphyrins at different ratios: Ni100-Zn0, Ni75-Zn25, Ni50-Zn50, Ni25-Zn75, and Ni0-Zn100.

***Characterization techniques***
NMR spectra were recorded at 298 K (unless stated otherwise) on an Agilent-400 MR DD2 spectrometer (400 MHz). 1H NMR chemical shifts (δ) are given in parts per million (ppm) and were referenced to tetramethylsilane (0.00 ppm). Coupling constants are reported as J values in Hertz (Hz). Data for 1H NMR spectra are reported as follows: chemical shift (multiplicity, coupling constant, integration). Multiplicities are abbreviated as s (singlet) and d (doublet). FT-IR spectra were recorded on a PerkinElmer Spectrum 100 FT-IR Spectrometer with an universal ATR accessory over a range of 4000 to 650 cm-1. TGA analyses were performed from 30 to 860 °C under a nitrogen atmosphere at a heating rate of 10 °C⋅min-1 using a Perkin Elmer TGA 4000. Prior to the measurement, the samples were degassed at 130 °C for one hour under a nitrogen atmosphere. Liquid UV-vis spectra were recorded at 298 K on a PerkinElmer Lambda 35 UV-vis spectrometer (quartz cuvette) at a concentration of 5 μM in DMF. Prior to the measurements, the COF-DMF suspensions were sonicated for 30 minutes at room temperature. Nitrogen isotherms were measured on the NOVAtouch gas sorption analyzer from Quantachrome Instruments with high purity N2 (99.99%) at 77 K. Prior to the sorption measurements; all samples were degassed at 130 °C under vacuum for 16 h. The Quantachrome VersaWin software package was used for calculations of pore size distributions by fitting the nitrogen adsorption isotherms to the quenched solid density functional theory (QSDFT) carbon model (using slit/cylindrical/spherical pores). No smoothing factor was applied for the PSD calculation. X-ray photoemission spectroscopy (XPS) measurements were performed using a monochromatic Al Kα excitation source with a Thermo Scientific K-Alpha spectrometer. The spectrometer was calibrated using the C 1s adventitious carbon with a binding energy of 284.8 eV. The base pressure at the analysis chamber was about 2 × 10–9 mbar. The spectra were recorded using a spot size of 400 μm at a pass energy of 50 eV and a step size of 0.1 eV. PXRD patterns were measured on a Rigaku MiniFlex 600 powder diffractometer using a Cu-Kα source (λ = 1.5418 Å) over the 2θ range of 2 ° to 40 ° with a scan rate of 1 °⋅minute-1. For high-resolution transmission electron microscopy analysis, a FEI cubed Cs corrected Titan was used. HREM Lattice images are collected on a Thermo Scientific CetaTM 16M. A low intensity on the camera was used to avoid beam damage. In scanning mode (STEM) ADF (Annular Dark Field) images are collected. In this mode, a sub nm beam is scanned on the electron transparent sample and for each beam position the diffracted electrons are collected on a ring shape detector. On heavy/thicker parts of the sample, more diffracted electrons are collected, showing up bright in the image. Elemental mapping in STEM mode was done, using the super-X in the  ChemiSTEMTM configuration. The EDX spectrum is collected for each beam position in a STEM image. The accelerating voltage during STEM and TEM was 300 kV. COF framework degradation was observed after prolonged exposure under this beam. Therefore, images and elemental maps were collected in the first few 1-3 minutes, before the onset of degradation. For TEM sample preparation, the COF powder was crushed in a mortar first without and then under some ethanol. The dispersion was ultrasonically shaken for 5 minutes. Using a pipette, the dispersion was drop casted onto a C foil supported with a Cu grid (holey Quantifoil TEM grid). After drying, the grid was ready for TEM inspection. Scanning electron microscopy (SEM) images were recorded with a JEOL JSM-840 SEM: materials were deposited onto a sticky carbon surface on a flat sample holder, vacuum-degassed, and sputtered with gold at a thickness of 15 nm. Electrocatalysis: Preparation of deposited COF complexes onto electrodes: The mixture of each COF compound (7 mg) in DMF (4 mL) with 5 wt.% Nafion was sonicated for 40 min to obtain a well-mixed suspension. Then, the mixture was stirred at room temperature overnight and subsequently drop-casted onto a gas diffusion electrode (GDE, Sigracet 38 BC, 5% PTFE applied non-woven carbon paper with a microporous layer; 2.5 cm x 2.5 cm) for the membrane electrode assembly (MEA) study. For the H-cell setup, 10 µL of the prepared suspension was drop-casted on the pre-prepared surface (d = 3.0 mm) of a standard glassy carbon electrode and let to dry for 24 hours. All potentials were reported versus the Ag/AgCl reference electrode. Potentials were changed from Ag/AgCl (3 M KCl) to the reversible hydrogen electrode (RHE, ERHE=EAg/AgCl + 0.059 × pH + 0.210). Characterizations during electroreduction: The reduced products observed in the cathodic compartment were periodically collected from the reaction headspace and tested by gas chromatography (GC). The concentration of gaseous products (CO, CH4, H2) was obtained from GC, and the average of 4 injections was used to calculate their Faradaic efficiencies. The gas product from CO2 electroreduction was analyzed using a chromatograph (InterScience PerkinElmer Clarus 680) coupled with two thermal conductivity detectors (TCD) and a flame ionization detector (FID), while the liquid product was analyzed using HPLC (Infinity 1260 II LC, Agilent Technologies, Hi-Plex H column (at 50 °C) with VWD (at 210 nm and 280 nm) and RID (at 40 °C)) (Figures S12 and S13). 1H NMR was measured using a Bruker 400 MHz setup and the data were processed in MestreNova. The chemical shifts (δ) are reported in ppm. H-cell and membrane electrode assembly (MEA) experiments: To evaluate the electroactivity of the synthesized COF complexes, the electrochemical reduction of CO2 was first studied with an H-cell using the Linear Sweep Voltammetry (LSV) technique. The two-compartment H-cell comprised of a three-electrode configuration, including the immobilized COF catalysts on a glassy carbon working electrode (GCE), a silver/silver chloride (Ag/AgCl) reference electrode, and a platinum (Pt) counter electrode in a CO2-saturated 0.1 M KHCO3 aqueous solution. Gas-phase products were collected from the reaction headspace and measured using gas chromatography (GC). For experiments with higher current densities, a membrane electrode assembly (MEA) electrolyzer consisting of an anode chamber (Ni-foam anode, Recemat BV) with a liquid phase anolyte (0.5 M KOH) and a cathode chamber (COF on GDE) with a gas phase inlet was employed (schematic shown at Figure S22). The membrane that separates these chambers is a Sustainion anion-exchange membrane (X37-50 Grade RT). In this design, gaseous CO2 is delivered directly (at 40 ml min-1, STP) to the active materials through an inlet located at the back side of the GDE.

***Description of the data in this data set***
The data included in this data set has been organised per sample and per characterization technique.
The files follow the nomenclature system: Nix,Zny with x and y being the different ratios used in the synthesis of the COF materials
[type of characterization technique] can be any of the techniques listed under ***Characterization techniques***
[type of sample] can be: Ni100,Zn0 ; Ni75,Zn25 ; Ni50,Zn50 ; Ni25,Zn75 ; Ni0,Zn100 ; Ni100 plus Zn100 ; Blank
All .xlsx and .csv files contain A and B columns corresponding to the X and Y axis respectievly of the plots shown in the image folder.

***Data specific information***
General abbreviations mentioned in the first row of the .xlsx and .csv files:
[°] angle between sample and detector
[cps] counts per second
[K-M Absorbance] Kubelke-Munk Absorbance
[°C] degrees Celsius
[K] Kelvin
[M] molar
[Hz] Hertz
[nm] nanometer
[P/P0] relative pressure, ratio of measured pressure over saturation pressure from P0 cell
[cm3] cubic centimeter
[g] grams
[a.u.] arbitrary units
[cm-1] reciprocal centimeters
[Å] Angtroms, 10^-10 meters
[V] Voltage
[A] Ampere
