Reconciling of experimental and theoretical insights on the electroactive behavior of C/Ni nanoparticles with AuPt alloys for hydrogen evolution efficiency and Non-enzymatic sensor

We focused on a new feasible strategy for fabricating carbon-coated nickel (C/Ni) nanoparticles (NPs) with a AuPt alloy system using an integrated pulsed laser irradiation and ultrasonochemical process and provided insights on transferable electrocatalytic active surface states for HER and the selective detection of 1,4-benzenediol. The detailed physical characterization and electrochemical analyses revealed that the C/Ni–AuPt (0.12 mg/mL of AuPt) alloy showed exceptional electrocatalytic activities for HER in acidic media, with a low overpotential of 0.131 V at 10 mA/cm2, an exchange current density of 0.125 mA/cm2, a Tafel slope of 66 mV/dec, and a Tafel constant of 0.060 V. Additionally, an optimized C/Ni–AuPt electrocatalyst showed a broad dynamic linear response (50–250 μM) with high sensitivity (0.1134 μAμM−1cm−2) and low detection limit (0.185 μM) for sensing 1,4-benzenediol. Furthermore, an optimized C/Ni–AuPt alloys exhibited excellent electrochemical performance, long-term durability, and structural stability owing to the electronic effect of effective charge transfer from Au to Pt atoms, caused by a shift in the d-band center of Pt in AuPt alloys. The addition of C/Ni increased the active-sites of AuPt alloys because of the synergistic effect. Consequently, they provided abundant electrochemically active-surface areas necessary for the good dispersion of AuPt alloys. Alternatively, the strain effect was negligible in the C/Ni–AuPt structure. DFT calculations revealed that placing C/Ni NPs in direct contact with AuPt alloys displaces the d-band center of Au and Pt closer to the Fermi level, implying an increased activity of the electrocatalytic performance.