ABSTRACT
The key role of morphological defects (e.g., irregular steps and dislocations) on the selectivity of model Cu catalysts for the electrocatalytic reduction of CO2 (CO2RR) is illustrated here. Cu(111) single-crystal surfaces prepared under ultrahigh vacuum (UHV) conditions and presenting similar chemical and local microscopic surface features were found to display different product selectivity during the CO2RR. In particular, changes in selectivity from hydrogen-dominant to hydrocarbon-dominant product distributions were observed based on the number of CO2RR electrolysis pretreatment cycles performed prior to a subsequent UHV surface regeneration treatment, which lead to surfaces with seemingly identical chemical composition and local crystallographic structure. However, significant mesostructural changes were observed through a micron-scale microscopic analysis, including a higher density of irregular steps on the samples producing hydrocarbons. Thus, our findings highlight that step edges are key for C-C coupling in the CO2RR and that not only atomistic but also mesoscale characterization of electrocatalytic materials is needed in order to comprehend complex selectivity trends.
ABSTRACT
Electrocatalyst surfaces prepared under ultrahigh vacuum (UHV) conditions can create model surfaces to better connect theoretical calculations with experimental studies. The development of a single crystal sample holder and inert electrochemical cells prepared with modularity and chemical stability in mind would allow for expensive single crystals to be reused indefinitely in both UHV and electrochemical settings. This sample holder shows reproducible surface preparations for single crystal samples and consistent electrochemical experiments without the introduction of impurities into the surface. The presented setup has been used as a critical piece for the characterization of Cu(111) surfaces under CO2 electrochemical reduction reaction conditions as a test case.
ABSTRACT
The identification of the active sites for the electrochemical reduction of CO2 (CO2 RR) to specific chemical products is elusive, owing in part to insufficient data gathered on clean and atomically well-ordered electrode surfaces. Here, ultrahigh vacuum based preparation methods and surface science characterization techniques are used with gas chromatography to demonstrate that subtle changes in the preparation of well-oriented Cu(100) and Cu(111) single-crystal surfaces drastically affect their CO2 RR selectivity. Copper single crystals with clean, flat, and atomically ordered surfaces are predicted to yield hydrocarbons; however, these were found experimentally to favor the production of H2 . Only when roughness and defects are introduced, for example by electrochemical etching or a plasma treatment, are significant amounts of hydrocarbons generated. These results show that structural and morphological effects are the key factors determining the catalytic selectivity of CO2 RR.
ABSTRACT
Digital health technologies for people with epilepsy (PWE) include internet-based resources and mobile apps for seizure management. Since non-pharmacological interventions, such as listening to specific Mozart's compositions, cognitive therapy, psychosocial and educational interventions were shown to reduce epileptic seizures, these modalities can be integrated into mobile software and delivered by mobile medical apps as digital therapeutics. Herein, we describe: (1) a survey study among PWE about preferences to use mobile software for seizure control, (2) a rationale for developing digital therapies for epilepsy, (3) creation of proof-of-concept mobile software intended for use as an adjunct digital therapeutic to reduce seizures, and (4) broader applications of digital therapeutics for the treatment of epilepsy and other chronic disorders. A questionnaire was used to survey PWE with respect to preferred features in a mobile app for seizure control. Results from the survey suggested that over 90% of responders would be interested in using a mobile app to manage their seizures, while 75% were interested in listening to specific music that can reduce seizures. To define digital therapeutic for the treatment of epilepsy, we designed and created a proof-of-concept mobile software providing digital content intended to reduce seizures. The rationale for all components of such digital therapeutic is described. The resulting web-based app delivered a combination of epilepsy self-care, behavioral interventions, medication reminders and the antiseizure music, such as the Mozart's sonata K.448. To improve long-term patient engagement, integration of mobile medical app with music and multimedia streaming via smartphones, tablets and computers is also discussed. This work aims toward development and regulatory clearance of software as medical device (SaMD) for seizure control, yielding the adjunct digital therapeutic for epilepsy, and subsequently a drug-device combination product together with specific antiseizure medications. Mobile medical apps, music, therapeutic video games and their combinations with prescription medications present new opportunities to integrate pharmacological and non-pharmacological interventions for PWE, as well as those living with other chronic disorders, including depression and pain.
