not-yet-known not-yet-known not-yet-known unknown 4.6 Electrochemical measurements HER performance was measured through an electrochemical workstation (CH Instruments, CHI660E). Graphite rod, Ag/AgCl (3M NaCl filled), and carbon paper of 1 × 1 cm2, which was coated by the electrocatalysts, were used as a counter, reference, and working electrode, respectively. Pt wire with 1 mm diameter was only used as the reference electrode for Pt decoration. In the case of MoSe2-P samples, the electrode was prepared by a drop casting method in the same manner as the 4.4 section. All electrochemical properties were estimated in 0.5 M H2SO4 electrolyte (pH = 0.3) The conversion potential RHE was calculated using a following equation: ERHE=EAg/AgCl+EAg/AgCl0+0.059 × pH (1) where EAg/AgCl and EAg/AgCl0 are the potential measured using Ag/AgCl reference electrode and the standard potential (0.209 V) at 25 °C. Given that the pH is 0.3 and Equation (1), ERHE can be expressed as: ERHE = EAg/AgCl + 0.2267 V (2) The LSV curves were conducted at a scan rate of 5 mV/s with 85% iR correction. Tafel slopes were extracted from the obtained LSV curves. Cdl and ECSA were estimated from CV curves with different scan rates of 10, 20, 30, 40, 50, and 60 mV/s in the RHE potential range of 0.3667 to 0.4867 V. Cdl and ECSA can be expressed as follows: [25] Cdl= (Ja-Jc)/2 (3) ECSA= Cdl/Cs (4) where Ja and Jc are the anodic and cathodic current densities at 0.4267 V and Cs indicates the specific capacitance (0.04 mF/cm2). [26] Specific activity can be calculated as: Specific activity = j/ECSA (5) where j is current density in LSV curve. EIS was performed at –0.17 V vs. RHE within a frequency range from 1MHz to 0.01 Hz for estimating the Rct, where AC amplitude was set as 5 mV. Chronopotentiometry was carried out at current densities of 10, 20, 30, 40, and 50 mA/cm2 for each 2 h to validate the electrocatalysts’ durability.