Constructing 1D Boron Chains in the Structure of Transition Metal Monoborides for Hydrogen Evolution Reactions
TL;DR: In this article, transition metal monoborides (CrB and WB) with different arrangement of one-dimensional (1D) boron chains were synthesized under high pressures and high temperatures.
Abstract: The forms of boron atoms are many and varied in the structure of transition metal borides (TMBs). The form of boron atoms determines the structure, morphology, and properties of borides. Herein, transition metal monoborides (CrB and WB) with different arrangement of one-dimensional (1D) boron chains were synthesized under high pressures and high temperatures. The 1D boron chains between the interlayers of CrB are parallel to one another, while the 1D boron chains between the interlayers of WB are perpendicular to one another. The morphologies of CrB and WB also show large differences due to the difference in 1D boron chain arrangement. As electrocatalysts for hydrogen evolution reactions (HERs), CrB and WB show good catalysis activity and durability. WB has the smallest overpotential (210 mV) and Tafel slope (90.09 mV dec−1), which is mainly attributed to the intercrossing boron chains improving the electrical properties of WB, as well as the 5d electrons of W being more chemically active. The TOF value of WB is 1.35 s−1, proving that WB has a higher intrinsic catalytic activity during HERs. This work provides a data reference for the development of high-efficiency electrocatalysts.
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TL;DR: In this paper , a new strategy is proposed to compose integral bulk electrodes with needle surfaces in transition metal borides (TMBs) for hydrogen evolution reaction (HER), which is significant for developing new kinds of bulk TMBs catalysts.
Abstract: Transition metal borides (TMBs) are promising catalysts for hydrogen evolution reaction (HER). While the commercially available TMBs indicate poor HER performance due to powder electrode and low activity sites density, optimizing commercial TMBs for better HER performance is urgent. To break through the challenge, a new strategy is proposed to compose integral bulk electrodes with needle surfaces in TMBs. The integral bulk electrodes in TiB2, ZrB2, and HfB2 are formed under high pressure and high temperature (HPHT), and the nanoneedle morphology is constructed by chemical etching. In the three materials, the smallest overpotential is 346 mV at 10 mA cm−2 in the HCl etched bulk TiB2 electrode, which is about 61.9% higher than commercial TiB2 powder. Better performance arises from better conductivity of the integral bulk electrode, and the nano morphology exposes the edge sides of the structure which have high activity site density. This work is significant for developing new kinds of bulk TMBs catalysts.
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TL;DR: In this article , a two-phase system was proposed for the synthesis of higher tungsten boride WB5-x in the vacuumless direct current atmospheric arc discharge plasma.
Abstract: We proposed an efficient method toward the synthesis of higher tungsten boride WB5-x in the vacuumless direct current atmospheric arc discharge plasma. The crystal structure of the synthesized samples of boron-rich tungsten boride was determined using computational techniques, showing a two-phase system. The ab initio calculations of the energies of various structures with similar X-ray diffraction (XRD) patterns allowed us to determine the composition of the formed higher tungsten boride. We determined the optimal parameters of synthesis to obtain samples with 61.5% WB5-x by volume. The transmission electron microscopy measurements showed that 90% of the particles have sizes of up to 100 nm, whereas the rest of them may have sizes from 125 to 225 nm. Our study shows the possibility of using the proposed vacuumless method as an efficient and inexpensive way to synthesize superhard WB5-x without employing resource-consuming vacuum techniques.
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TL;DR: It is shown that an abundant material, polymeric carbon nitride, can produce hydrogen from water under visible-light irradiation in the presence of a sacrificial donor.
Abstract: The production of hydrogen from water using a catalyst and solar energy is an ideal future energy source, independent of fossil reserves. For an economical use of water and solar energy, catalysts that are sufficiently efficient, stable, inexpensive and capable of harvesting light are required. Here, we show that an abundant material, polymeric carbon nitride, can produce hydrogen from water under visible-light irradiation in the presence of a sacrificial donor. Contrary to other conducting polymer semiconductors, carbon nitride is chemically and thermally stable and does not rely on complicated device manufacturing. The results represent an important first step towards photosynthesis in general where artificial conjugated polymer semiconductors can be used as energy transducers.
9,751 citations
TL;DR: Biesinger et al. as mentioned in this paper proposed a more consistent and effective approach to curve fitting based on a combination of standard spectra from quality reference samples, a survey of appropriate literature databases and/or a compilation of literature references and specific literature references where fitting procedures are available.
7,498 citations
TL;DR: Recent developments in the search for innovative materials with high hydrogen-storage capacity are presented.
Abstract: Mobility — the transport of people and goods — is a socioeconomic reality that will surely increase in the coming years. It should be safe, economic and reasonably clean. Little energy needs to be expended to overcome potential energy changes, but a great deal is lost through friction (for cars about 10 kWh per 100 km) and low-efficiency energy conversion. Vehicles can be run either by connecting them to a continuous supply of energy or by storing energy on board. Hydrogen would be ideal as a synthetic fuel because it is lightweight, highly abundant and its oxidation product (water) is environmentally benign, but storage remains a problem. Here we present recent developments in the search for innovative materials with high hydrogen-storage capacity.
7,414 citations
TL;DR: This Review introduces several typical energy storage systems, including thermal, mechanical, electromagnetic, hydrogen, and electrochemical energy storage, and the current status of high-performance hydrogen storage materials for on-board applications and electrochemicals for lithium-ion batteries and supercapacitors.
Abstract: [Liu, Chang; Li, Feng; Ma, Lai-Peng; Cheng, Hui-Ming] Chinese Acad Sci, Inst Met Res, Shenyang Natl Lab Mat Sci, Shenyang 110016, Peoples R China.;Cheng, HM (reprint author), Chinese Acad Sci, Inst Met Res, Shenyang Natl Lab Mat Sci, 72 Wenhua Rd, Shenyang 110016, Peoples R China;cheng@imr.ac.cn
4,105 citations
TL;DR: A catalyst that forms upon the oxidative polarization of an inert indium tin oxide electrode in phosphate-buffered water containing cobalt (II) ions is reported that not only forms in situ from earth-abundant materials but also operates in neutral water under ambient conditions.
Abstract: The utilization of solar energy on a large scale requires its storage. In natural photosynthesis, energy from sunlight is used to rearrange the bonds of water to oxygen and hydrogen equivalents. The realization of artificial systems that perform "water splitting" requires catalysts that produce oxygen from water without the need for excessive driving potentials. Here we report such a catalyst that forms upon the oxidative polarization of an inert indium tin oxide electrode in phosphate-buffered water containing cobalt (II) ions. A variety of analytical techniques indicates the presence of phosphate in an approximate 1:2 ratio with cobalt in this material. The pH dependence of the catalytic activity also implicates the hydrogen phosphate ion as the proton acceptor in the oxygen-producing reaction. This catalyst not only forms in situ from earth-abundant materials but also operates in neutral water under ambient conditions.
3,695 citations