1. General Information
- **Data Set Title**: Nickel nitride/nitrogen-doped carbon composite as an efficient bifunctional electrocatalyst for water splitting
- **Authors**:
-Principal investigator and contact person: Anna Ilnicka, Faculty of Chemistry, Nicolaus Copernicus University in Torun, Gagarina 7, 87-100 Torun, Poland, e-mail: ailnicka@umk.pl
-Investigator: Laura Kubinska, Faculty of Chemistry, Nicolaus Copernicus University in Torun, Gagarina 7, 87-100 Torun, Poland, e-mail: 307382@stud.umk.pl
-Investigator: Patrycja Grabowska, Faculty of Chemistry, Nicolaus Copernicus University in Torun, Gagarina 7, 87-100 Torun, Poland, e-mail: pgrabowska@doktorant.umk.pl
-Investigator: Mariusz Szkoda, Faculty of Chemistry, Department of Chemistry and Technology of Functional Materials, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk, Poland, Advanced Materials Center, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk, Poland, e-mail: mariusz.szkoda@pg.edu.pl
-Investigator: Marta Gajewska, Academic Centre for Materials and Nanotechnology, AGH University of Krakow, Mickiewicza 30, 30-059 Kraków, Poland, e-mail: marta.gajewska@agh.edu.pl
- **Date of data collection**: 2025 year
- **Place of data collection**: Torun, Krakow
- **Keywords***: transition metal nitrides, nitrogen-doped carbon, hydrogen evolution reaction, oxygen evolution reaction
Data language**: English
- **Sources of funding**: National Science Center (NCN) OPUS UMO-2024/53/B/ST5/02770
2. Overview of data and files
- **Folders List**:
1. Raman spectra - containing Raman spectra recorded using a Renishaw InVia Raman spectrometer equipped with a 532 nm excitation laser operating at a power of 2 mW. Folder contain raw data files in .dpt format.
2. High‑resolution transmission electron microscopy (HRTEM) images - containing high‑resolution transmission electron microscopy images recorded using a FEI Tecnai TF20 X‑TWIN microscope equipped with a field‑emission gun (FEG).
The microscope was operated at an accelerating voltage of 200 kV. Folder contains raw data files in .tiff format.
3. Energy dispersive spectroscopy (EDS) spectra - containing EDS spectra recorded using a FEI Tecnai TF20 X‑TWIN microscope equipped with a field‑emission gun (FEG).
The microscope was operated at an accelerating voltage of 200 kV. The elemental distribution was determined using energy‑dispersive spectroscopy (EDS). Folder contains raw data files in .txt format.
4. X-Ray diffractograms - containing analysis X-ray diffractograms recorded using a Philips X’Pert diffractometer equipped with an X’Celerator Scientific detector.
The scans were recorded over a 2θ range of 10°–110°, with a step size of 0.02° and a counting time of 0.48 s per step, using Cu Kα radiation (λ = 1.5406 Å) at 40 kV and 30 mA. Folder contains raw data files in .xy format.
5. Chronoamperograms - were recorded using the potentiostat–galwanostat system of a BioLogic VSP electrochemical workstation under EC-Lab V11.43 software control.
The synthesized catalysts were evaluated using a three-electrode system where catalysts were used as the working electrode, a platinum mesh as a counter electrode, and Ag/AgCl (3.0 M KCl) as the reference electrode.
To fabricate the electrochemical testing electrode, the mixture of 3 mg catalyst, 750 µL of distilled water, 200 µL of isopropyl alcohol, and 50 µL of 5 wt% Nafion solution was sonicated for 30 min to obtain an ink.
Finally, 2.8 µL of the fresh catalyst ink was dropped onto a glassy carbon electrode (2 mm) and dried at room temperature with a loading 0.268 mg cm⁻2. Tests were conducted at a constant current density of 10 mA cm⁻2 for 24 h in 1.0 M KOH aqueous electrolyte. Folder contains raw data files in .txt format.
6. Linear sweep voltammograms - were recorded using the potentiostat–galwanostat system of a BioLogic VSP electrochemical workstation under EC-Lab V11.43 software control.
The synthesized catalysts were evaluated using a three-electrode system where catalysts were used as the working electrode, a platinum mesh as a counter electrode, and Ag/AgCl (3.0 M KCl) as the reference electrode.
To fabricate the electrochemical testing electrode, the mixture of 3 mg catalyst, 750 µL of distilled water, 200 µL of isopropyl alcohol, and 50 µL of 5 wt% Nafion solution was sonicated for 30 min to obtain an ink.
Finally, 2.8 µL of the fresh catalyst ink was dropped onto a glassy carbon electrode (2 mm) and dried at room temperature with a loading 0.268 mg cm⁻2. Voltammograms were recorded for HER and OER at scan rates of 5 mV s⁻1 in 1.0 M KOH aqueous electrolyte. Folder contains raw data files in .txt format.
- **Sample Name List**:
- Ni3N: the catalyst was synthesized by dissolving nickel(II) nitrate hexahydrate (878 mg, Ni(NO3)2·6H2O) and urea (909 mg, CO(NH2)2) in 60 mL of deionized water. After stirring for 30 min, the solution was transferred to a hydrothermal reactor and heated at 120 °C for 5 h. The resulting product was washed with ethyl alcohol and dried at 50 °C. Next, it was placed in a tube furnace and heated at 350 °C for 2 h with a heating rate of 5 °C min−1 under an ammonia (NH3) atmosphere.
- C: nitrogen-doped carbon material was synthesized by thoroughly mixing 2.5 g of lysine, 5.5 g of K2CO3, and 2.5 g of methylcellulose in 50 mL of distilled water. Lysine, a nitrogen-rich amino acid (containing two amine groups and one carboxyl group), served as both the carbon and nitrogen precursor, enabling in-situ incorporation of nitrogen into the carbon framework during thermal treatment. K2CO3 acted as a chemical activating agent, promoting the development of a porous structure, while methylcellulose provided an additional carbon source and acted as a structure-directing agent. The resulting suspension was dried at 100 °C until the solvent was completely removed, forming a solid gel that was subsequently placed in a porcelain boat. The dried precursor was then thermally treated at 800 °C with a heating rate of 10 °C min−1 and a holding time of 1 h under an N2 atmosphere. Pyrolysis under inert gas prevented oxidation and facilitated the conversion of nitrogen-containing functional groups from lysine into pyridinic nitrogen species within the carbon matrix. After thermal treatment, the sample was slowly cooled in the furnace to room temperature with a linearly decreasing temperature. The obtained carbonized product was then etched with concentrated hydrochloric acid to remove residual potassium species, followed by extensive washing with distilled water on a Büchner funnel until the filtrate reached a neutral pH.
- Ni3N_C(X): to obtain coposite cathalysts 100 mg of Ni3N and 5, 10, 15, or 20 mg of carbon were mixed in a mortar and ground for 10–15 min, yielding samples appropriately denoted as Ni3N_C(5), Ni3N_C(10), Ni3N_C(15), and Ni3N_C(20).
3. Sharing and access information
- **Licenses/Restrictions**: CC BY - Creative Commons Attribution 4.0.
- **Related Publication**: L. Kubinska, P. Grabowska, M. Szkoda, M. Gajewska, A. Ilnicka, Nickel nitride/nitrogen-doped carbon composite as an efficient bifunctional electrocatalyst for water splitting, Journal of Power Sources, 2026, 693, 241144.
