Highly Durable Nanoporous Cu2−xS Films for Efficient Hydrogen Evolution Electrocatalysis under Mild pH Conditions

# Dataset of “ Highly Durable Nanoporous Cu2-xS Films for Efficient Hydrogen Evolution Electrocatysis under Mild pH Conditions”

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## GENERAL INFORMATION

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1. Dataset title: “ Highly Durable Nanoporous Cu2-xS Films for Efficient Hydrogen Evolution Electrocatysis under Mild pH Conditions”

2. Authorship:  

    Name: Roser Fernández-Climent  

    Institution: Institute of Advanced Materials (INAM), Universitat Jaume I, 12006 Castelló, Spain

    ORCID: 0009-0003-4184-5579

    Name: Jesús Redondo

    Institution: Department of Polymers and Advanced Materials, Centro de Física de Materiales, University of the Basque Country UPV/EHU, 20018 San Sebastián, Spain; Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, 180 00 Prague 8, Czech Republic

    Name: Miguel Garcia-Tecedor

    Institution: Institute of Advanced Materials (INAM), Universitat Jaume I, 12006 Castelló, Spain; Photoactivated Processes Unit, IMDEA Energy Institute, Parque Tecnológico de Móstoles, 28935 Móstoles, Madrid, Spain;

    ORCID: 0000-0002-9664-4665

    Name: Maria Chiara Spadaro

    Institution:  Catalan Institute of Nanoscience and Nanotechnology (ICN2) and BIST Campus UAB, Bellaterra 08193 Barcelona, Spain;

    ORCID: 0000-0002-6540-0377

    Name: Junan Li

    Institution: Department of Chemistry, Université de Montréal, Montréal, QC H2V 0B3, Canada

    ORCID: 0000-0002-3660-1049

    Name: Daniel Chartrand

    Institution: Department of Chemistry, Université de Montréal, Montréal, QC H2V 0B3, Canada

    Name: Frederik Schiller

    Institution: Centro de Física de Materiales and Material Physics Center CSIC/UPV-EHU, 20018 San Sebastián, Spain; Donostia International Physics Center, 20018 San Sebastián, Spain

    ORCID: 0000-0003-1727-3542

    Name: Jhon Pazos

    Institution: Research Cluster on Converging Sciences and Technologies (NBIC), Departamento de Ingeniería Electrónica, Universidad Central, Bogotá 110311, Colombia

    ORCID: 0000-0001-7570-9047

    Name: Mikel F. Hurtado

    Institution: Research Cluster on Converging Sciences and Technologies (NBIC), Departamento de Ingeniería Electrónica, Universidad Central, Bogotá 110311, Colombia; Materials Chemistry Area, Civil Engineering Department, Corporación Universitaria Minuto de Dios, Calle 80, Main Sede Bogotá, Colombia. − Nanotechnology Applications Area, Environmental Engineering Department, Universidad Militar Nueva Granada, Zipaquirá 110311, Colombia

    Name: Victor de la Peña O’Shea

    Institution: Photoactivated Processes Unit, IMDEA Energy Institute, Parque Tecnológico de Móstoles, 28935 Móstoles, Madrid, Spain;

    ORCID: 0000-0001-5762-4787

    Name: Nikolay Kornienko

    Institution: Department of Chemistry, Université de Montréal, Montréal, QC H2V 0B3, Canada;

    ORCID: 0000-0001-7193-2428

    Name: Jordi Albiol

    Institution: Catalan Institute of Nanoscience and Nanotechnology (ICN2) and BIST Campus UAB, Bellaterra 08193 Barcelona, Spain; ICREA, 08010 Barcelona, Catalonia, Spain

    ORCID: 0000-0002-0695-1726

    Name: Sara Barja

    Institution: Department of Polymers and Advanced Materials, Centro de Física de Materiales, University of the Basque Country UPV/EHU, 20018 San Sebastián, Spain; Donostia International Physics Center, 20018 San Sebastián, Spain; IKERBASQUE, Basque Foundation for Science, 48009 Bilbao, Spain;

    Email: [e-mail]

    Name: Camilo A. Mesa

    Institution: Institute of Advanced Materials (INAM), Universitat Jaume I, 12006 Castelló, Spain; Research Cluster on Converging Sciences and Technologies (NBIC), Departamento de Ingeniería Electrónica, Universidad Central, Bogotá, 110311, Colombia;

    Email:  

    ORCID: 0000-0002-8450-2563

    Name: Sixto Giménez

    Institution: Institute of Advanced Materials (INAM), Universitat Jaume I, 12006 Castelló, Spain

    Email:  

    ORCID: 0000-0002-4522-3174

## FILE DESCRIPTION

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### Figure 2

-Fig2e.txt : XPS analysis for Cu LMM.

-Fig2f.txt : XPS analysis for S 2p spectra of the Cu2−xS electrodes. Reference spectra measured on a metallic Cu substrate are shown in red dotted lines.

### Figure 3

-Fig3a.txt : Chronoamperometric measurement at −1 V vs RHE of the Cu2−xS catalyst for 28 days of continuous operation. The dashed gray line represents the quasi-linear increase in the catalytic current density as a function of operation time. Steady-state currents at −1.0 V vs RHE normalized by the electrochemical surface area (ECSA) are shown as light blue empty dots.

-Fig3b.txt : Linear sweep voltammograms (LSV), measured at 20 mV s−1, of the same Cu2−xS electrode as a function of operation time between day 1, i.e., freshly synthesized catalyst (darker blue), and after 28 days (lighter blue) of continuous operation. Inset: zoom between the first and the last LSV to compare the overpotential at −10 mA cm−2 (dashed red line).

-Fig3c.txt : Cathodic current densities (|J|) measured at −1.0 V vs RHE,from panel (b) (blue filled dots) compared to the ECSA increase ratio (empty green dots, RECSA) calculated using eq 1. Note that the time is in the log scale.

-Fig3d.txt : Series (RS) and charge transfer (RCT) resistances and capacitance, RS (gray dots), RCT (violet dots), and C (green dots) at the 28th day of measurement. The gray area denotes the potential region where RCT < RS.

-Fig3f.txt : Tafel slope values as a function of operation time obtained from panel.

###Figure 4

-Fig4a.txt : Differential optical density spectra of the Cu2−xS (light and dark blue) and reference Cu foil (light and dark red) electrodes as a function of potential. For reference, Cu2−xS differential spectra were measured also in 0.1 M TBAP in acetonitrile.

-Fig4b.txt : Operando XRD diffractograms at different potentials from OCP to −1.0 V vs RHE.

-Fig4bInset.txt : Inset:LSV.

-Fig4c.txt : Reference XPS measurements for (c) Cu LMM and (d) S 2p spectra. 

-Fig4d.txt : Post electrochemical XPS measurements for (c) Cu LMM and (d) S 2p spectra.

### Figure S2

-FigS2f.txt : UV-Vis-NIR absorption spectrum of the pristine Cu2-xS films, extracted from diffuse reflectance measurements. The NIR band centered ~1600 nm is tentatively assigned to localized surface plasmon resonance caused by the Cu deficiency as observed in other Cu2-xS electrodes

### Figure S4

-FigS4a.txt : XPS analysis of the Cu2-xS as-synthetized electrodes before (black) and after (red) Ar+ cleaning. Cu 2p spectra.

-FigS4b.txt : XPS analysis of the Cu2-xS as-synthetized electrodes before (black) and after (red) Ar+ cleaning. Normalized Cu 2p spectra.

-FigS4c.txt : XPS analysis of the Cu2-xS as-synthetized electrodes before (black) and after (red) Ar+ cleaning. Cu Auger spectra.

-FigS4d.txt : XPS analysis of the Cu2-xS as-synthetized electrodes before (black) and after (red) Ar+ cleaning. O 1s spectra.

-FigS4e.txt : XPS analysis of the Cu2-xS as-synthetized electrodes before (black) and after (red) Ar+ cleaning. C 1s spectra.

-FigS4f.txt : XPS analysis of the Cu2-xS as-synthetized electrodes before (black) and after (red) Ar+ cleaning. S 2p spectra.

### Figure S9

-FigS9.txt : Real part of the complex capacitance measured as a function of frequency (Bode plots) of our Cu2-xS electrodes a function of operation time measured at -0.1 V vs RHE (non-faradaic region). The Cdl values were taken at ~5 Hz.

### Figure S10

-FigS10.txt : Normalized linear sweep voltammograms (LSV) by the rECSA values from Figure 3c of the same Cu2-xS electrode as a function of operation time between the day 1, i.e., freshly synthesized catalyst (darker blue) and after 28 days (lighter blue) of continuous operation. LSVs from Figure 3b are displayed in the inset for reference. The LSV were measured at 20 mV s-1 in 0.1 M KHCO3.

-FigS10Inset.txt : Linear sweep voltammograms (LSV), measured at 20 mV s−1, of the same Cu2−xS electrode as a function of operation time between day 1, i.e., freshly synthesized catalyst (darker blue), and after 28 days (lighter blue) of continuous operation.

### Figure S12

-FigS12.txt : Rs values of the Cu2-xS catalysts extracted from electrochemical impedance spectroscopy (EIS) analysis as a function of operation time (indicated by the grey arrow),inset: Rs values of the Cu2S catalysts measured as a function of concentration of KHCO3 electrolyte. A 20-fold increase of the KHCO3 concentration results in a decrease of ~1 order of magnitude in the Rs, thus, the observed ohmic drop decrease can be attributed to an increase in ionic concentration in the electrolyte. Rs can aid understanding the difference between the 8-fold increase in J, compared to the 6.5-fold increase in ECSA shown in Figure 3c. However, this is out of the scope if this paper and is being subject of further analysis.

### Figure S13

-FigS13a.txt : Charge transfer resistances (Rct)

-FigS13b.txt : Capacitances values as a function of operation time from the Cu2-xS electrocatalysts.

### Figure S14

-FigS14.txt : Steady-state LSVs of the Cu2-xS electrode as a function of operation time between the day 1, i.e., freshly synthesized catalyst (darker blue) and after 28 days (lighter blue) of continuous operation (indicated by the grey arrow). Every data point corresponds to the average current of the last 60 s of a 5-minute chronoamperometric measurement at every measured potential.

### Figure S16

-FigS16a.txt : Differential spectra of the reference Cu foil as a function of applied potential.

-FigS16b.txt : Differential spectra of the Cu2-xS and reference electrodes as a function of applied potential.

### Figure S17

-FigS17a.txt : XPS analysis of the Cu2-xS electrodes after the electrochemical measurements. Cu Auger spectra when transferred under air (black) and under N2 atmospheres (red).

-FigS17b.txt : XPS analysis of the Cu2-xS electrodes after the electrochemical measurements. C 1s spectra when transferred under air (black) and under N2 atmospheres (red).

-FigS17c.txt : XPS analysis of the Cu2-xS electrodes after the electrochemical measurements. O 1s spectra when transferred under air (black) and under N2 atmospheres (red).

-FigS17d.txt : XPS analysis of the Cu2-xS electrodes after the electrochemical measurements. 2p spectra when transferred under air (black) and under N2 atmospheres (red).

### Figure S18

-FigS18a.txt :  XPS analysis of the Cu2-xS electrodes after the electrochemical measurements with and without washing with water.

-FigS18b.txt :  XPS analysis of the Cu2-xS electrodes after the electrochemical measurements with and without washing with water.

-FigS18c.txt :  XPS analysis of the Cu2-xS electrodes after the electrochemical measurements with and without washing with water.