Kinetic‐Oriented Construction of MoS2 Synergistic Interface to Boost pH‐Universal Hydrogen Evolution

2019-12-10T06:32:28+00:00December 10th, 2019|Categories: Publications|Tags: , , |

The rational design of the interfacial electrocatalyst heterostructure MoS2 is guided by the kinetics investigation. By optimizing the electronic structure based on the simultaneous modulation of the 3d‐band‐offsets of Ni, Co, and Mo near the interface, superior pH‐universal hydrogen evolution performances are achieved, which opens up a new strategy in the design of highly efficient electrocatalysts. Abstract As a prerequisite for a sustainable energy economy in the future, designing earth‐abundant MoS2 catalysts with a comparable hydrogen evolution catalytic performance in both acidic and alkaline environments is still an urgent challenge. Decreasing the energy barriers could enhance the catalysts’ activity but is not often a strategy for doing so. Here, the first kinetic‐oriented design of the MoS2‐based heterostructure is presented for pH‐universal hydrogen evolution catalysis by optimizing the electronic structure based on the simultaneous modulation of the 3d‐band‐offsets of Ni, Co, and Mo near the interface. Benefiting from this desirable electronic structure, the obtained MoS2/CoNi2S4 catalyst achieves an ultralow overpotential of 78 and 81 mV at 10 mA cm−2, and turnover frequency as high as 2.7 and 1.7 s−1 at the overpotential of 200 mV in alkaline and acidic media, respectively. The MoS2/CoNi2S4 catalyst represents one of the best hydrogen evolution reaction performing ones among MoS2‐based catalysts reported to date in both alkaline and acidic environments, and equally important is the remarkable long‐term stability with negligible activity loss after maintaining at 10 mA cm−2 for 48 h in both acid and base. This work highlights the potential to deeply understand and

Published in: "Advanced Functional Materials".

Energy Transport by Radiation in Hyperbolic Material Comparable to Conduction

2019-12-10T06:31:57+00:00December 10th, 2019|Categories: Publications|Tags: , |

Energy transport by electromagnetic waves inside hyperbolic material boron nitride is investigated. A microscopic many‐body model is developed and shows that radiative heat transfer is in the same order of magnitude as phononic heat transfer. Experiments on total thermal transport provide the same conclusion, and radiative transfer accounts for a larger fraction of total energy transport at higher temperatures. Abstract Radiation as a heat transfer mode inside a bulk material is usually negligible in comparison to conduction. Here, the contribution of radiation to energy transport inside a hyperbolic material, hexagonal boron nitride (hBN), is investigated. With hyperbolic dispersion, i.e., opposite signs of dielectric components along principal directions, phonon polaritons contribute significantly to energy transport due to a much greater number of propagating modes compared to that in a normal material. A many‐body model is developed to account for radiative heat transfer in a material with a nonuniform temperature distribution. The total radiative heat transfer through hBN is found to be largely contributed by the high‐κ modes within the Reststrahlen bands, and is comparable to phonon conduction. Experimental measurements of temperature‐dependent thermal transport also show that radiative contribution to thermal transport is of the same order as that from phonons. Therefore, this work shows, for the first time, radiative heat transfer inside a material can be comparable to phonon conductive heat transfer.

Published in: "Advanced Functional Materials".

Mechanically Robust Gel Polymer Electrolyte for an Ultrastable Sodium Metal Battery

2019-12-10T04:35:24+00:00December 10th, 2019|Categories: Publications|Tags: , , |

Gel polymer electrolyte with addition of an appropriate amount of graphene oxide content demonstrates excellent mechanical strength and high ionic conductivity, being crucial to the sodium dendrite inhibition and satisfactory rate performance. As a result, uniform sodium deposition and stable reversible sodium plating/stripping at a high current density of 5 mA cm−2 are achieved over a testing period of 400 h. Abstract Sodium dendrite growth is responsible for short circuiting and fire hazard of metal batteries, which limits the potential application of sodium metal anode. Sodium dendrite can be effectively supp