Doctor of Philosophy, University of Texas Austin (2016)
Bachelor of Science, Stanford University, CHEM-BS (2012)
Bachelor of Science, Stanford University, MATSC-MIN (2012)
William Chueh, Postdoctoral Faculty Sponsor
Exceptional electrocatalytic oxygen evolution via tunable charge transfer interactions in La0.5Sr1.5Ni1-xFexO4±δ Ruddlesden-Popper oxides.
2018; 9 (1): 3150
The electrolysis of water is of global importance to store renewable energy and the methodical design of next-generation oxygen evolution catalysts requires a greater understanding of the structural and electronic contributions that give rise to increased activities. Herein, we report a series of Ruddlesden-Popper La0.5Sr1.5Ni1-xFexO4±δ oxides that promote charge transfer via cross-gap hybridization to enhance electrocatalytic water splitting. Using selective substitution of lanthanum with strontium and nickel with iron to tune the extent to which transition metal and oxygen valence bands hybridize, we demonstrate remarkable catalytic activity of 10 mA cm-2 at a 360 mV overpotential and mass activity of 1930 mA mg-1ox at 1.63 V via a mechanism that utilizes lattice oxygen. This work demonstrates that Ruddlesden-Popper materials can be utilized as active catalysts for oxygen evolution through rational design of structural and electronic configurations that are unattainable in many other crystalline metal oxide phases.
View details for PubMedID 30089833
View details for PubMedCentralID PMC6082882
An ultrafast nickel-iron battery from strongly coupled inorganic nanoparticle/nanocarbon hybrid materials
Ultrafast rechargeable batteries made from low-cost and abundant electrode materials operating in safe aqueous electrolytes could be attractive for electrochemical energy storage. If both high specific power and energy are achieved, such batteries would be useful for power quality applications such as to assist propelling electric vehicles that require fast acceleration and intense braking. Here we develop a new type of Ni-Fe battery by employing novel inorganic nanoparticle/graphitic nanocarbon (carbon nanotubes and graphene) hybrid materials as electrode materials. We successfully increase the charging and discharging rates by nearly 1,000-fold over traditional Ni-Fe batteries while attaining high energy density. The ultrafast Ni-Fe battery can be charged in ~2 min and discharged within 30 s to deliver a specific energy of 120 Wh kg(-1) and a specific power of 15 kW kg(-1). These features suggest a new generation of Ni-Fe batteries as novel devices for electrochemical energy storage.
View details for DOI 10.1038/ncomms1921
View details for PubMedID 22735445