Bi-Cheng Hu

Iron Carbide Nanoparticles Encapsulated in Mesoporous Fe‐N‐Doped Carbon Nanofibers for Efficient Electrocatalysis

Exploring low-cost and high-performance nonprecious metal catalysts (NPMCs) for oxygen reduction reaction (ORR) in fuel cells and metal-air batteries is crucial for the commercialization of these energy conversion and storage devices. Here we report a novel NPMC consisting of Fe3 C nanoparticles encapsulated in mesoporous Fe-N-doped carbon nanofibers, which is synthesized by a cost-effective method using carbonaceous nanofibers, pyrrole, and FeCl3 as precursors. The electrocatalyst exhibits outstanding ORR activity (onset potential of -0.02 V and half-wave potential of -0.140 V) closely comparable to the state-of-the-art Pt/C catalyst in alkaline media, and good ORR activity in acidic media, which is among the highest reported activities of NPMCs.

Dyeing bacterial cellulose pellicles for energetic heteroatom doped carbon nanofiber aerogels

The energy crisis and environmental pollution are serious challenges that humanity will face for the long-term. Despite tremendous efforts, the development of environmentally friendly methods to fabricate new energy materials is still challenging. Here we report, for the first time, a new strategy to fabricate various doped carbon nanofiber (CNF) aerogels by pyrolysis of bacterial cellulose (BC) pellicles which had adsorbed or were dyed with different toxic organic dyes. The proposed strategy makes it possible to remove the toxic dyes from waste-water and then synthesize doped CNF aerogels using the dyed BC pellicles as precursors. Compared with other reported processes for preparing heteroatom doped carbon (HDC) nanomaterials, the present synthetic method has some significant advantages, such as being green, general, low-cost and easily scalable. Moreover, the as-prepared doped CNF aerogels exhibit great potential as electrocatalysts for the oxygen reduction reaction (ORR) and as electrode materials for supercapacitors.

Synthesis of Low Pt-Based Quaternary PtPdRuTe Nanotubes with Optimized Incorporation of Pd for Enhanced Electrocatalytic Activity

Improving heteroatomic interactions via alloying or forming heterogeneous catalysts is of importance to the enhancement in terms of electrocatalytic activity and stability. In this work, a simple galvanic replacement reaction was utilized to synthesize low Pt-based quaternary nanotubes (NTs). It is easy to obtain PtPdRuTe NTs with different composition and controlled shape using ultrathin Te nanowires (NWs) as sacrificial templates for its high activity. The NT wall thickness and formed NPs on the surface are closely related with the composition, especially Pd content. The optimized incorporation of Pd atoms into ternary PtRuTe NTs formed a uniform protecting PtPd surface and modified the Pt electronic structure to improve the methanol oxidation reaction (MOR) performance. X-ray photoelectron spectroscopy (XPS) reveals a larger extent of electron transfer from neighboring atoms to Pt on PtPdRuTe, consequently leading to a weaker bonding of the intermediate on Pt. As a result, the quaternary PtPdRuTe NTs exhibit enhanced activity and stability toward efficient MOR.

A mixed-solvent route to unique PtAuCu ternary nanotubes templated from Cu nanowires as efficient dual electrocatalysts

Forming alloys with transition metal remarkably decreases the u sage of noble metal and offers benefits for electrocatalysis. Here we introduced a mixed-solvent strategy to synthesize unique PtAuCu ternary nanotubes (NTs) with porous and rough surface, using high quality Cu nanowires (NWs) as the partial sacrificial templates. We found that Au plays a key role in the enhancement of e lectrocatalytic performance for both methanol oxidation reaction (MOR) and formic acid oxidation reaction (FAOR). The mass activities of PtAuCu NTs after acid leaching for MOR and FAOR reach 1698.8 mA mgPt−1 at 0.9 V and 1170 mA mgPt−1 at 0.65 V, respectively. Such ternary NTs show impressive stability due to the irreversibly adsorption of CO* on the Au surface instead of the active Pt surface and the excellent structure stability. The present method could be extended to prepare other new multi-functional electrocatalysts.摘要与非贵金属形成合金是一种能大幅减少电催化剂中贵金属用量的有效方法, 且形成合金有利于催化性能提升. 本文引入了一种混合溶剂体系, 通过采用高质量铜纳米线作为部分牺牲模板合成了多孔均一, 表面粗糙的PtAuCu三元纳米管. 实验表明金的引入是催化剂甲醇氧化(MOR)和甲酸氧化(FAOR)性能提升的一个关键因素. 其MOR和FAOR质量活性分别达到了1698.8 mA mgPt−1(0.9V)和1170 mA mgPt−1(0.65V). 由于CO*不可逆的吸附在金的表面而非有催化活性的铂表面, 这种三元纳米管催化剂表现出了优异的催化稳定性和结构稳定性. 此外, 这种合成方法可以用于合成其他的新型双功能催化剂.

SiO2-protected shell mediated templating synthesis of Fe–N-doped carbon nanofibers and their enhanced oxygen reduction reaction performance

Electrocatalytic reduction of oxygen plays a crucial role in many energy storage and conversion devices. Currently, the development of high-performance carbon-based non-precious-metal (NPM) oxygen reduction reaction (ORR) catalysts in acidic media still remains a great challenge. Herein, we report a highly active meso/microporous Fe–N-doped carbon nanofiber (Fe–N-CNF) catalyst prepared via a SiO2-protected shell mediated template method. The SiO2-protected shell not only restricts the free migration of iron species but also traps volatile gaseous substances during the pyrolysis process at high temperature, thus leading to a simultaneous optimization of both the surface functionalities and porous structures of the Fe–N-CNF catalysts. Compared to catalysts prepared without a SiO2-protected shell, the Fe–N-CNF catalysts exhibit a much enhanced ORR activity in an acidic medium, along with a superior long-term stability.

Emerging Carbon-Nanofiber Aerogels: Chemosynthesis versus Biosynthesis

Carbon aerogels that are typically prepared using sol-gel chemistry have unique three dimensional networks of interconnected nanometer-sized particles and thus exhibit many fascinating physical properties and great application potentials in widespread fields. To boost the practical applications, it is necessary to develop efficient and low-cost methods to produce high-performance carbon aerogels on a large-scale, preferably in a sustainable way. In 2012, two new classes of aerogels consisting of carbon-nanofiber (CNF) networks were prepared from biomass-derived precursors by chemosynthesis (i.e. template-directed hydrothermal carbonization of carbohydrate) and biosynthesis (i.e. use of bacterial cellulose as precursor), respectively. This Review gives a critical overview of this emerging and rapidly developing field, focusing on the synthetic strategies of the carbon-nanofiber aerogels and their outstanding physical properties. We also discuss the multifunctional application potentials of the two sorts of carbon aerogels and their nanocomposites, and highlight the challenges and future opportunities in this field.

Wood-Derived Ultrathin Carbon Nanofiber Aerogels

Carbon aerogels with 3D networks of interconnected nanometer-sized particles exhibit fascinating physical properties and show great application potential. Efficient and sustainable methods are required to produce high-performance carbon aerogels on a large scale to boost their practical applications. An economical and sustainable method is now developed for the synthesis of ultrathin carbon nanofiber (CNF) aerogels from the wood-based nanofibrillated cellulose (NFC) aerogels via a catalytic pyrolysis process, which guarantees high carbon residual and well maintenance of the nanofibrous morphology during thermal decomposition of the NFC aerogels. The wood-derived CNF aerogels exhibit excellent electrical conductivity, a large surface area, and potential as a binder-free electrode material for supercapacitors. The results suggest great promise in developing new families of carbon aerogels based on the controlled pyrolysis of economical and sustainable nanostructured precursors.

A mixed-solvent route to unique PtAuCu ternary nanotubes templated from Cu nanowires as efficient dual electrocatalysts@@@在混合溶剂中以铜纳米线为模板制备高效双功能三元PtAuCu纳米管电催化剂

Forming alloys with transition metal remarkably decreases the u sage of noble metal and offers benefits for electrocatalysis. Here we introduced a mixed-solvent strategy to synthesize unique PtAuCu ternary nanotubes (NTs) with porous and rough surface, using high quality Cu nanowires (NWs) as the partial sacrificial templates. We found that Au plays a key role in the enhancement of e lectrocatalytic performance for both methanol oxidation reaction (MOR) and formic acid oxidation reaction (FAOR). The mass activities of PtAuCu NTs after acid leaching for MOR and FAOR reach 1698.8 mA mgPt−1 at 0.9 V and 1170 mA mgPt−1 at 0.65 V, respectively. Such ternary NTs show impressive stability due to the irreversibly adsorption of CO* on the Au surface instead of the active Pt surface and the excellent structure stability. The present method could be extended to prepare other new multi-functional electrocatalysts.摘要与非贵金属形成合金是一种能大幅减少电催化剂中贵金属用量的有效方法, 且形成合金有利于催化性能提升. 本文引入了一种混合溶剂体系, 通过采用高质量铜纳米线作为部分牺牲模板合成了多孔均一, 表面粗糙的PtAuCu三元纳米管. 实验表明金的引入是催化剂甲醇氧化(MOR)和甲酸氧化(FAOR)性能提升的一个关键因素. 其MOR和FAOR质量活性分别达到了1698.8 mA mgPt−1(0.9V)和1170 mA mgPt−1(0.65V). 由于CO*不可逆的吸附在金的表面而非有催化活性的铂表面, 这种三元纳米管催化剂表现出了优异的催化稳定性和结构稳定性. 此外, 这种合成方法可以用于合成其他的新型双功能催化剂.