Possible reasons for unsatisfactory Cdl results:

• Experimental issues:Electrode cleanliness: Make sure your working electrode is clean and free of contamination. Contaminants can affect the double-layer capacitance. Electrolyte purity: Use high-purity 1M KOH solution to minimize impurities that could influence capacitance measurements. Measurement technique: Double-check your cyclic voltammetry (CV) parameters like scan rate and potential window. Ensure they are appropriate for Cdl measurements in your system.
• Data analysis issues:Background subtraction: Ensure proper background subtraction during data analysis to isolate the double-layer current. Fitting method: Verify that you're using the appropriate method to fit the capacitance data and extract Cdl values.

Improving your Cdl measurements:

• Consult the literature: Look for research papers that report Cdl measurements for HER catalysts in 1M KOH. These papers might provide valuable insights into experimental setups and data analysis techniques.
• Control experiments: Perform control experiments with well-characterized electrodes (like Pt) in 1M KOH to ensure your measurement setup is functioning correctly.
• Advanced characterization techniques: Consider using complementary techniques like electrochemical impedance spectroscopy (EIS) alongside CV to obtain a more complete picture of the electrode-electrolyte interface.

Here are some additional resources that might be helpful:

• ResearchGate example of HER tests in 1M KOH: Link to HER tests in 1 m KOH. a) The HER polarization curves for as‐prepared... on ResearchGate

By carefully considering these points and potentially refining your experimental approach and data analysis, you should be able to obtain more satisfactory Cdl results for your HER studies in 1M KOH.