Designing AgBi3S5 as an efficient electrocatalyst for hydrogen evolution reaction†
Abstract
A facile fast synthetic route is designed to prepare a versatile nano-electrocatalyst AgBi3S5 (ABS) for the generation of green fuel, H2, via water electrolysis. The XRD pattern confirms the major formation of monoclinic phase AgBi3S5 (ABS) along with binary phase Ag2S (AS) and Bi2S3 (BS). Another variant CuBiS2(CBS) nanoparticle is synthesized to compare the electrochemical result with the unique sustainable as-synthesized nanoparticles of the ABS compound. Microscopy (HR-TEM) and spectroscopy (FTIR) studies provide confirmational evidence of the syntheses of ABS, AS, BS, and CBS, respectively, while an XPS study confirms the presence of Ag, Bi, and S in ABS. From the electrochemical analysis, it is evident that ABS shows a lower overpotential value of 47 mV compared to those of other variants (AS – 93 mV, BS – 191 mV, CBS – 603 mV) and lower Tafel slope values (mV dec−1) (75.99) than the others (AS – 101.54, BS – 120.29, CBS – 265.2), which are key aspects in analyzing the catalytic activity performance of the catalyst. It is also proved that the rate-determining step of the reaction proceeds through the Volmer–Heyrovsky step. A lower EIS value of 9.84 Ω with a higher active surface area value of 0.092 cm2 for ABS indicate superior and effective electron charge transfer kinetics on the electrode–electrolyte interface and elevated activity compared to the other electrocatalysts (AS – 15.24 Ω and 0.035 cm2, BS – 16.01 Ω and 0.014 cm2, and CBS – 19 Ω and 0.005 cm2). On top of that, an acceleration degradation (AD) study before and after analysis performed at 100 mVs−1 for 500 cycles in acidic solution discloses the fact when comparing the two LSV curves there is a small hike (8 mV at 10 mA cm−2), suggesting higher stability and low catalyst degradation for ABS. Chronoamperometric studies with a fixed applied potential of −0.065 V vs. RHE also reveal that the catalyst (ABS) shows retention of activity after a 72 hour long-term process in a cathodic environment.