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The development of cost-effective hydroxide exchange membrane fuel cells is limited by the lack of high-performance and low-cost anode hydrogen oxidation reaction catalysts. Here we report a Pt-free catalyst Ru7Ni3/C, which exhibits excellent hydrogen oxidation reaction activity in both rotating disk electrode and membrane electrode assembly measurements. The hydrogen oxidation reaction mass activity and specific activity of Ru7Ni3/C, as measured in rotating disk experiments, is about 21 and 25 times that of Pt/C, and 3 and 5 times that of PtRu/C, respectively. The hydroxide exchange membrane fuel cell with Ru7Ni3/C anode can deliver a high peak power density of 2.03 W cm−2 in H2/O2 and 1.23 W cm−2 in H2/air (CO2-free) at 95 °C, surpassing that using PtRu/C anode catalyst, and good durability with less than 5% voltage loss over 100 h of operation. The weakened hydrogen binding of Ru by alloying with Ni and enhanced water adsorption by the presence of surface Ni oxides lead to the high hydrogen oxidation reaction activity of Ru7Ni3/C. By using the Ru7Ni3/C catalyst, the anode cost can be reduced by 85% of the current state-of-the-art PtRu/C, making it highly promising in economical hydroxide exchange membrane fuel cells.

Hydrogen is considered by many to be a promising energy currency, particularly for the transportation sector and for mobile devices. To realize a hydrogen-based fuel economy, hydrogen must be produced in an efficient and sustainable manner. In this article, single-layer nickel hydroxide (Ni(OH) 2 )-nanosheet-assisted Pt/C catalysis for the hydrogen evolution reaction (HER) in an alkaline environment was investigated. The HER activity trajectories of the hybrid catalysts in correlation with the composition and morphology of Ni(OH) 2 were explored in depth. By optimizing the Volmer step through addition of single-layer Ni(OH) 2 into Pt/C catalysis, this hybrid catalyst manifests a 110% increase of the HER activity by using only 20 wt % single-layer Ni(OH) 2 with a lithium ion additive as compared to the state-of-the-art Pt/C catalyst. Density functional theory calculations revealed that the single-layer Ni(OH) 2 behaves superior in adsorption ability of OH − when compared with multilayer Ni(OH) 2 . The single-layer Ni(OH) 2 contributes to dual improvement on both the Volmer step and the adsorption of OH − during HER.

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Hydroxide exchange membrane fuel cells (HEMFC) are a promising power source for automobiles due to their low cost. Here we focus on improving the beginning-of-life performance of HEMFCs to a higher level with poly(aryl piperidinium) (PAP) membranes and ionomers. We find that lower RH and backpressure in anode than cathode can eliminate anode flooding and cathode dryout so that a balanced water management can be achieved. We also find that PtRu/C is a better anode catalyst than Pt/Ketjen Black due to the presence of Ru and Pt/Vulcan XC-72 is a better cathode catalyst than Pt/Ketjen Black due to its better mass transport properties. Once the preferred operating conditions and materials incorporated into the same cell, our HEMFCs achieved a peak power density of 1.89 W cm −2 in H 2 /O 2 and 1.31 W cm −2 in H 2 /air.

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Hydroxide exchange membrane fuel cells (HEMFCs) are a potentially lower-cost hydrogen fuel cell technology; however, ambient levels of CO2 in air significantly reduce HEMFCs’ performance. In this work, we demonstrate an electrochemically-driven CO2 separator (EDCS) which can be used to remove ambient levels of CO2 from air upstream of the HEMFC stack in fuel cell vehicles, protecting it from CO2-related performance losses. The EDCS operating window was explored for current density, anode flow, and cathode flow with respect to its impact on CO2 separation performance. Additionally, gas-phase mass transport was improved by selecting flow fields and gas diffusion layers conducive to the EDCS operating regime. The use of a carbon-ionomer interlayer at the cathode was explored and improved CO2 removal performance from 77.7% to 98.2% at 20 mA cm−2. An analytical, 1-D model is used to explain the experimental observations and design improvements. A single-cell, 25 cm2 EDCS using the aforementioned improved design demonstrated greater than 98% CO2 removal at a cathode flow rate of 1300 sccm for 100 h with 2.7% hydrogen stack consumption.

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