This text describes the data presented in the paper: Photochemical Enhancement in Catalytic Activity of Nickel Nanoparticles for Hydration of CO2 ======================== Introductory information ======================== Files included in the data deposit (include a short description of what data are contained): All the data has been the put in one Excel file with different page headings. Description to the various page headings are as follows 1)Figure 1b: EDX data for nickel nanoparticles 2)Figure 2a: The change in pH of DI water (squares) and a suspension of NiNPs (circle) when CO2 is bubbled through it in the presence of artificial light. 3)Figure 2b: The change in pH of DI water (squares) and a suspension of NiNPs (circle) when CO2 is bubbled through it in the dark. 4)Figure 3: pH change profile when CO2 is bubbled in DI water or a suspension of NiNPs with light but in the presence of an IR filter. 5)Figure 4a: XPS spectrum of NiNPs before bubbling of CO2 under solar irradiation without an IR filter 6)Figure 4b: XPS spectrum of NiNPs after bubbling of CO2 under solar irradiation without an IR filter 7)Figure 5: UV-Vis absorption spectrum of a 30 ppm suspension of NiNPs. Explain the relationship between multiple data sets, if required:None Key words used to describe the data: XPS, pH change, CO2 hydration, photocatalysis, UV absorbance ========================== Methodological information ========================== A brief method description – what the data is, how and why it was collected or created, and how it was processed: Nickel nanoparticles were purchased from Nano Technologies (Korea) and 99% pure CO2 from BOC (UK). The DI water used throughout had a conductivity of <0.1 µS.cm-1 (DC 9, Purite UK). An Oriel Instruments (Newport Corporation, UK) solar simulator with a 150 W (Xe, Ozone Free) arc lamp was used to provide the simulated solar radiation. The power of the lamp was measured using a power meter (Thorlabs, Germany) measuring wavelengths between 535-1550 nm. The solar simulator had a power intensity of 47-50 mW/cm2 over this range. An Oriel Instruments Model 6117 IR filter was used to remove the IR region of the spectrum, where appropriate. The power of the lamp with the IR filter in place was measured to be 41-45 mW/cm2 between the wavelengths of 535-1550 nm. The emission spectra for the Xe arc lamp with and without the filter is presented in the Supplementary Information. Clear silica glass jars of 250 ml were purchased from LS industries. A HI2550 (Hanna Instruments, UK) pH meter with a computer auto-log was used to record the pH of the samples every 10 seconds. TEM specimens were produced by suspending the NiNPs in DI water and casting a single drop on a lacey carbon coated Cu grid (300 mesh, Agar Scientific). The HRTEM of the NiNPs was carried out at Durham University using a JOEL 2100F field emission gun instrument operating at 200kV. The experimental procedure to test the CO2 hydration was similar to that outlined by Bhaduri and Šiller[1]. The NiNP suspension used had a concentration of 30 ppm of NiNPs in 200 ml of DI water. The suspensions were prepared by adding 6 mg of NiNPs to the DI water followed by 5 min ultra-sonication in a Hilsonic sonicator. For the control reaction 200 ml of DI water was used without NiNPs. CO2 was bubbled through the samples at a constant rate in all experiments (1.69 mM min-1, at 1 atm). The concentration of 30 ppm of NiNPs was chosen because of the maximum uptake of CO2 has previously been observed at this concentration [1]. The distance between the light source (200-2500 nm) and the sample was ~38 cm and was kept constant for all experiments. The power intensity measurements were carried out at the same distance from the light source. The pH meter was calibrated before each experimental run. The data log was started when the pH probe and thermocouple was introduced in DI water (or NiNP suspension) and CO2 gas was only introduced when the data log had a stable value for over 1 min. The sample vial was cooled using a fan to ensure constant temperature. All the experiments were performed at a temperature of 20 °C in a dark room. Due to light sensitivity of the pH probe (Ag/AgCl reference electrode) the pH meter was calibrated under relative darkness (using minimal light of a single LED diode) for the experiments requiring complete darkness or in the presence of the solar simulator for those requiring light. After a steady pH value was observed (stable for 1 min) CO2 gas was introduced and the pH profiles recorded. Each experiment under different lighting conditions (i.e., with IR filter, without IR filter and in the dark) was repeated four times. In order to test the catalytic activity of NiNPs the difference between the catalysed and uncatalysed pH profiles was analysed by comparing the area between the pH profiles. The UV-Vis absorption experiments were carried out using a UV-spectrophotometer (Spectrostar Nano, BMG Labtech, UK). The sample for UV-Vis measurements had a concentration of 30 ppm NiNPs suspended in DI water prepared by the method mentioned above. Instruments, hardware and software used: Described above. Date(s) of data collection: Between July 2012-December 2014 Geographic coverage of data:UK Data validation (how was the data checked, proofed and cleaned):All experiments were repeated in a set of four and average data is presented. XPS and UV-Visible absorbance was done only once. Overview of secondary data, if used: ========================= Data-specific information ========================= Definitions of names, labels, acronyms or specialist terminology uses for variables, records and their values: NiNPs- Nickel nanoparticles XPS- X-ray photoelecton spectroscopy B.E.- Binding energy B.G.- Background DI Water- Deionized water Explanation of weighting and grossing variables: N/A Outline any missing data: N/A ======= Contact ======= Please contact rdm@ncl.ac.uk for further information