Lignin-derived bimetallic platinum group metal-free oxygen reduction reaction electrocatalysts for acid and alkaline fuel cells

Litchi‐derived platinum group metal‐free electrocatalysts for oxygen reduction reaction and hydrogen evolution reaction in alkaline media

“…Moreover, one of the crucial properties of electrocatalysts, especially the ones that are made from waste products, is their operative stability. To test HER stability on Ni–Co 900, an accelerated stability test was used 78,79 . In this measurement, 2000 voltammetric cycles with the scan rate of 50 mV s −1 were executed.…”

“…The cell was equipped with a glassy carbon disk as a working electrode (glassy carbon with a geometric area of 0.1963 cm 2 ), which was mounted on a RDE equipment (Pine WaveVortex RDE system coupled with a Pine bipotentiostat) and had a rotation speed of 1600 rpm, a saturated calomel electrode (SCE) as a reference electrode, and a Pt wire as the counter electrode. The inks were prepared by mixing (5 mg) of electrocatalyst with 985 μL of isopropanol and 15 μL of 5 wt% Nafion D‐520 ionomer solution as reported previously 78 . For each measurement, 0.6 mg cm −2 ink was deposited over GC disk.…”

“…To test HER stability on Ni-Co 900, an accelerated stability test was used. 78,79 In this measurement, 2000 voltammetric cycles with the scan rate of 50 mV s −1 were executed. Meanwhile, the polarization curves at the first cycle and after every 500 cycles were measured with a 5 mV s −1 scan rate; the scans are reported in (Figure S2).…”

“…Related to the stability test for ORR, 2000 cycles accelerated stability test was performed over Fe 600 sample, whereas the potential window and electrolytic conditions remained as before. 78,79 As it was mentioned in the previous section, in this study, continuous potential cycling was conducted at a rate of 50 mV s −1 , whereas initial and every 500th scans were recorded at a rate of 5 mV s −1 and their results are shown in (Figure S3). The E on and E 1/2 did not show significant change over the continuous potential cycling, but by increasing the cycle number the reduction in the limiting current density could be observed.…”

“…The inks were prepared by mixing (5 mg) of electrocatalyst with 985 μL of isopropanol and 15 μL of 5 wt% Nafion D-520 ionomer solution as reported previously. 78 For each measurement, 0.6 mg cm −2 ink was deposited over GC disk. HER was performed in an alkaline media containing 1 M KOH.…”