TY - JOUR
T1 - Bidirectional energy & fuel production using RTO-supported-Pt-IrO2loaded fixed polarity unitized regenerative fuel cells
AU - Gayen, Pralay
AU - Liu, Xinquan
AU - He, Cheng
AU - Saha, Sulay
AU - Ramani, Vijay K.
N1 - Publisher Copyright:
© The Royal Society of Chemistry.
PY - 2021/5/21
Y1 - 2021/5/21
N2 - Fixed-polarity unitized regenerative fuel cells (FP-URFCs) are devices for energy conversion coupled with fuel production with low self-discharge, high energy densities, fast start-up/shut down dynamics, and long cycle-life. We have synthesized a bifunctional Pt-IrO2/RTO (ruthenium-titanium mixed oxide) electrocatalyst for the HOR/OER (hydrogen oxidation reaction/oxygen evolution reaction) wherein IrO2/RTO acts as an OER electrocatalyst, upon which the HOR active Pt electrocatalyst is deposited. Pt-IrO2/RTO shows higher OER (η@10 mA cm-2 = 0.26 ± 0.01 V, i = 67 ± 1.9 mA cm-2 at η = 0.32 V) and HOR (η@2.5 mA cm-2 = 0.01 V, i = 2.78 ± 0.11 mA cm-2 at η = 0.1 V) activity and higher stability in comparison to benchmark OER (RuO2, η@10 mA cm-2 = 0.42 ± 0.03 V, i = 3.1 ± 0.2 mA cm-2 at η = 0.32 V and IrO2, η@10 mA cm-2 = 0.33 ± 0.02 V, i = 10.2 ± 0.2 mA cm-2 at η = 0.32 V) and HOR (Pt/C, η@2.5 mA cm-2 = 0.05 V, i = 2.58 ± 0.08 mA cm-2 at 0.1 V vs. RHE) electrocatalysts, respectively. Pt-IrO2/RTO exhibits higher bifunctional HOR/OER activity as compared to both IrO2/RTO and RTO, which is achieved through a combined effect of enhanced active site density and favorable electronic interactions (increased metal oxidation states of Ru and Ir) as confirmed by XPS and UPS. The deposition of IrO2 in Pt-IrO2/RTO is responsible for high stability by lowering the dissolution of the RTO support, as confirmed by ICP-MS. A FP-URFC tested with Pt-IrO2/RTO and Pt/C as the anode and cathode, respectively yields a mass-specific activity of 1050 ± 22 A g-1 at 1.8 V and 20 ± 2 A g-1 at 0.9 V under electrolyzer and fuel cell modes, respectively. The FP-URFC shows a round-trip efficiency of 40.2% at 1 A cm-2 with low Pt-loading on both electrodes. Therefore, FP-URFCs using Pt-IrO2/RTO as the HOR/OER bifunctional electrocatalyst have significant potential towards efficient and cost-effective bidirectional energy and fuel production.
AB - Fixed-polarity unitized regenerative fuel cells (FP-URFCs) are devices for energy conversion coupled with fuel production with low self-discharge, high energy densities, fast start-up/shut down dynamics, and long cycle-life. We have synthesized a bifunctional Pt-IrO2/RTO (ruthenium-titanium mixed oxide) electrocatalyst for the HOR/OER (hydrogen oxidation reaction/oxygen evolution reaction) wherein IrO2/RTO acts as an OER electrocatalyst, upon which the HOR active Pt electrocatalyst is deposited. Pt-IrO2/RTO shows higher OER (η@10 mA cm-2 = 0.26 ± 0.01 V, i = 67 ± 1.9 mA cm-2 at η = 0.32 V) and HOR (η@2.5 mA cm-2 = 0.01 V, i = 2.78 ± 0.11 mA cm-2 at η = 0.1 V) activity and higher stability in comparison to benchmark OER (RuO2, η@10 mA cm-2 = 0.42 ± 0.03 V, i = 3.1 ± 0.2 mA cm-2 at η = 0.32 V and IrO2, η@10 mA cm-2 = 0.33 ± 0.02 V, i = 10.2 ± 0.2 mA cm-2 at η = 0.32 V) and HOR (Pt/C, η@2.5 mA cm-2 = 0.05 V, i = 2.58 ± 0.08 mA cm-2 at 0.1 V vs. RHE) electrocatalysts, respectively. Pt-IrO2/RTO exhibits higher bifunctional HOR/OER activity as compared to both IrO2/RTO and RTO, which is achieved through a combined effect of enhanced active site density and favorable electronic interactions (increased metal oxidation states of Ru and Ir) as confirmed by XPS and UPS. The deposition of IrO2 in Pt-IrO2/RTO is responsible for high stability by lowering the dissolution of the RTO support, as confirmed by ICP-MS. A FP-URFC tested with Pt-IrO2/RTO and Pt/C as the anode and cathode, respectively yields a mass-specific activity of 1050 ± 22 A g-1 at 1.8 V and 20 ± 2 A g-1 at 0.9 V under electrolyzer and fuel cell modes, respectively. The FP-URFC shows a round-trip efficiency of 40.2% at 1 A cm-2 with low Pt-loading on both electrodes. Therefore, FP-URFCs using Pt-IrO2/RTO as the HOR/OER bifunctional electrocatalyst have significant potential towards efficient and cost-effective bidirectional energy and fuel production.
UR - https://www.scopus.com/pages/publications/85106032469
U2 - 10.1039/d1se00103e
DO - 10.1039/d1se00103e
M3 - Article
AN - SCOPUS:85106032469
SN - 2398-4902
VL - 5
SP - 2734
EP - 2746
JO - Sustainable Energy and Fuels
JF - Sustainable Energy and Fuels
IS - 10
ER -