Tuning interfacial electric fields provides a powerful means to control electrocatalyst activity. Importantly, electric fields can modify adsorbate binding energies based on their polarizability and ...dipole moment, and hence operate independently of scaling relations that fundamentally limit performance. However, implementation of such a strategy remains challenging because typical methods modify the electric field non-uniformly and affects only a minority of active sites. Here we discover that uniformly tunable electric field modulation can be achieved using a model system of single-atom catalysts (SACs). These consist of M-N
active sites hosted on a series of spherical carbon supports with varying degrees of nanocurvature. Using in-situ Raman spectroscopy with a Stark shift reporter, we demonstrate that a larger nanocurvature induces a stronger electric field. We show that this strategy is effective over a broad range of SAC systems and electrocatalytic reactions. For instance, Ni SACs with optimized nanocurvature achieved a high CO partial current density of ~400 mA cm
at >99% Faradaic efficiency for CO
reduction in acidic media.
A platform of mechanotactic hybrids is established by projecting lateral gradients of apparent interfacial stiffness onto the planar surface of a compliant hydrogel layer using an underlying rigid ...substrate with microstructures inherited from 3D printed molds. Using this platform, the mechanistic coupling of epithelial migration with the stiffness of the extracellular matrix (ECM) is found to be independent of the interfacial compositional and topographical cues.
A simple and portable colorimetric assay for creatinine detection is fabricated based on the synergistic coordination of creatinine and uric acid with Hg2+ on the surface of gold nanoparticles, which ...exhibits good selectivity and sensitivity. Point‐of‐care clinical creatinine monitoring can be supported for monitoring renal function and diagnosing corresponding renal diseases at home.
The use of sunlight to drive organic reactions constitutes a green and sustainable strategy for organic synthesis. Herein, we discovered that the earth-abundant aluminum oxide (Al2O3) though ...paradigmatically known to be an insulator could induce an immense increase in the selective photo-oxidation of different benzyl alcohols in the presence of a large variety of dyes and O2. This unique phenomenon is based on the surface complexation of benzyl alcohol (BnOH) with the Brønsted base sites on Al2O3, which reduces its oxidation potential and causes an upshift in its HOMO for electron abstraction by the dye. The surface complexation of O2 with Al2O3 also activates the adsorbed O2 for receiving electrons from the photoexcited dyes. This discovery brings forth a new understanding on utilizing surface complexation mechanisms between the reactants and earth abundant materials to effectively achieve a wider range of photoredox reactions.
Chemicals manufacture is among the top greenhouse gas contributors. More than half of the associated emissions are attributable to the sum of ammonia plus oxygenates such as methanol, ethylene glycol ...and terephthalic acid. Here we explore the impact of electrolyzer systems that couple electrically-powered anodic hydrocarbon-to-oxygenate conversion with cathodic H
evolution reaction from water. We find that, once anodic hydrocarbon-to-oxygenate conversion is developed with high selectivities, greenhouse gas emissions associated with fossil-based NH
and oxygenates manufacture can be reduced by up to 88%. We report that low-carbon electricity is not mandatory to enable a net reduction in greenhouse gas emissions: global chemical industry emissions can be reduced by up to 39% even with electricity having the carbon footprint per MWh available in the United States or China today. We conclude with considerations and recommendations for researchers who wish to embark on this research direction.
Renewable electricity powered electrochemical CO
reduction (CO
R) offers a valuable method to close the carbon cycle and reduce our overreliance on fossil fuels. However, high purity CO
is usually ...required as feedstock, which potentially decreases the feasibility and economic viability of the process. Direct conversion of flue gas is an attractive option but is challenging due to the low CO
concentration and the presence of O
impurities. As a result, up to 99% of the applied current can be lost towards the undesired oxygen reduction reaction (ORR). Here, we show that acidic electrolyte can significantly suppress ORR on Cu, enabling generation of multicarbon products from simulated flue gas. Using a composite Cu and carbon supported single-atom Ni tandem electrocatalyst, we achieved a multicarbon Faradaic efficiency of 46.5% at 200 mA cm
, which is ~20 times higher than bare Cu under alkaline conditions. We also demonstrate stable performance for 24 h with a multicarbon product full-cell energy efficiency of 14.6%. Strikingly, this result is comparable to previously reported acidic CO
R systems using pure CO
. Our findings demonstrate a potential pathway towards designing efficient electrolyzers for direct conversion of flue gas to value-added chemicals and fuels.
Contact-mediated cell migration strongly determines the invasiveness of the corresponding cells, collective migration, and morphogenesis. The quantitative study of cellular response upon contact ...relies on cell-to-cell collision, which rarely occurs in conventional cell culture. Herein, we developed a strategy to activate a robust cell-to-cell collision within smooth muscle cell pairs. Nanomechanical traction force mapping reveals that the collision process is promoted by the oscillatory modulations between contraction and relaxation and orientated by the filopodial bridge composed of nanosized contractile machinery. This strategy can enhance the occurrence of cell-to-cell collision, which renders it advantageous over traditional methods that utilize micropatterned coating to confine cell pairs. Furthermore, modulation of the balance between cell tugging force and traction force can determine the repolarization of cells and thus the direction of cell migration. Overall, our approach could help to reveal the mechanistic contribution in cell motility and provide insights in tissue engineering.
Electrochemical CO2 reduction (CO2R) in acidic media with Cu‐based catalysts tends to suffer from lowered selectivity towards multicarbon products. This could in principle be mitigated using tandem ...catalysis, whereby the *CO coverage on Cu is increased by introducing a CO generating catalyst (e.g. Ag) in close proximity. Although this has seen significant success in neutral/alkaline media, here we report that such a strategy becomes impeded in acidic electrolyte. This was investigated through the co‐reduction of 13CO2/12CO mixtures using a series of Cu and CuAg catalysts. These experiments provide strong evidence for the occurrence of tandem catalysis in neutral media and its curtailment under acidic conditions. Density functional theory simulations suggest that the presence of H3O+ weakens the *CO binding energy of Cu, preventing effective utilization of tandem‐supplied CO. Our findings also provide other unanticipated insights into the tandem catalysis reaction pathway and important design considerations for effective CO2R in acidic media.
Tandem catalysis effects in electrochemical CO2 reduction were investigated through an isotopic labelling strategy involving the co‐reduction of 13CO2/12CO mixtures. The results provide evidence that tandem catalysis does indeed occur in neutral electrolyte but is curtailed under acidic conditions. This is due to Cu becoming less effective at utilizing tandem‐supplied CO in the presence of hydronium ions.
Programmable polymer substrates, which mimic the variable extracellular matrices in living systems, are used to regulate multicellular morphology, via orthogonally modulating the matrix topography ...and elasticity. The multicellular morphology is dependent on the competition between cell–matrix adhesion and cell–cell adhesion. Decreasing the cell–matrix adhesion provokes cytoskeleton reorganization, inhibits lamellipodial crawling, and thus enhances the leakiness of multicellular morphology.
Thermal runway constitutes the most pressing safety issue in lithium‐ion batteries and supercapacitors of large‐scale and high‐power density due to risks of fire or explosion. However, traditional ...strategies for averting thermal runaway do not enable the charging–discharging rate to change according to temperature or the original performance to resume when the device is cooled to room temperature. To efficiently control thermal runaway, thermal‐responsive polymers provide a feasible and reversible strategy due to their ability to sense and subsequently act according to a predetermined sequence when triggered by heat. Herein, recent research progress on the use of thermal‐responsive polymers to enhance the thermal safety of electrochemical storage devices is reviewed. First, a brief discussion is provided on the methods of preventing thermal runaway in electrochemical storage devices. Subsequently, a short review is provided on the different types of thermal‐responsive polymers that can efficiently avoid thermal runaway, such as phase change polymers, polymers with sol–gel transitions, and polymers with positive temperature coefficients. The results represent the important development of thermal‐responsive polymers toward the prevention of thermal runaway in next‐generation smart electrochemical storage devices.
Thermal‐responsive polymers provide a feasible and reversible strategy to efficiently control thermal runaway due to their ability to sense and subsequently act according to a predetermined sequence when triggered by heat. A short review is provided on using thermal‐responsive polymers to efficiently avoid thermal runaway, such as polymers with phase changes, polymers with sol–gel transitions, and polymers with a positive temperature coefficient.
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