Covalent Functionalization of Pristine and Ga-Doped Boron Phosphide Nanotubes with Imidazole

Abstract

Density functional theory (DFT) calculations at the B3LYP/6–31G* level were performed to investigate covalent functionalization of imidazole on pristine (in gas and H₂O phases) and Ga-doped BPNT models in terms of energetic, geometric, and electronic properties. The results show that imidazole, as a functional group, prefers to be adsorbed via its nitrogen atom on the pristine, Ga_B, and Ga_P nanotube models. The adsorption energy of imidazole on the (6,0) zigzag BPNT in gas and solvent phases is ?0.76 and ?1.11 eV, respectively, and about 0.38 and 0.43 electron are transferred from the imidazole to nanotube in the phases. The presence of a polar solvent increases the electron donor of imidazole molecule. The results show that Ga doping can significantly enhance the adsorption energy of imidazole on the nanotube models to about 95%.

Moreover, the imidazole adsorption on the pristine and Ga-doped BPNT models has not significant changes in the energy gap of the nanotube models and it is slightly changed after covalent functionalization process. This study may provide new insight to the development of functionalized boron phosphide nanotubes for generation of the new hybrid compounds especially in drug delivery systems for virtual applications.     

Phenol-formaldehyde resin route to the synthesis of several iron group transition metal phosphides

Abstract

A series of iron, cobalt and nickel metal phosphides of chemical formula Fe_xP, Co₂P and Ni₂P with high specific surface areas of 331.1, 294.2 and 228.0 m² g^?1, respectively, was firstly synthesized by phenol-formaldehyde resin route. It was found that the as-prepared Co₂P and Ni₂P samples synthesized using phenol-formaldehyde resin as a carbon source showed much higher BET surface areas than those prepared using other carbon sources reported before, including cinnamic strong alkali anion exchange resin, p-phenylenediamine and hexamethylenetetramine. This phenol-formaldehyde resin route was proved to be as universal as traditional H₂ reduction method.     

磷化镍催化剂的制备机理及其加氢脱氮性能

采用热重-质谱联用技术研究了次磷酸盐在氮气中的热分解过程,探讨了次磷酸盐热分解法制备磷化镍的反应机理:次磷酸镍中的Ni²⁺能够"催化"H₂PO₂^-低温发生歧化反应生成PH₃,继而还原Ni²⁺得到Ni₂P。制备了不同负载量的Ni₂P/SiO₂催化剂,用X射线衍射(XRD)、低温N₂吸附-脱附、高分辨透射电镜(HRTEM)等分析技术对催化剂结构进行表征。结果表明,Ni₂P活性组分在SiO₂载体上具有良好的分散性,颗粒粒径为5～8 nm。以喹啉为加氢脱氮模型化合物,在高压微型固定床反应器上对催化剂活性进行评价,在反应温度为360℃、氢气压力为2.0 MPa、液时空速为2.0 h^-1、氢油体积比为500:1时,Ni₂P(20%)/SiO₂催化剂的加氢脱氮率为41.5%。     

高分散Co0.2Ni1.6Fe0.2P助催化剂改性P掺杂g-C3N4纳米片高效光催化析氢的研究

随着化石燃料使用的增加和温室气体排放量持续上升,20世纪以来气温上升得更快。开发环境友好型能源取代传统化石燃料是当务之急。氢能源作为一种清洁、高效的能源,被认为是最有希望取代传统化石燃料的能源。光催化水分解水产氢作为为一种环保型技术被认为是最有前景的氢能生产方法。提高光生电子-空穴对分离效率是构建高效光催化剂的关键。然而,利用高度分散的助催化剂构建高效、稳定的产氢光催化剂仍然是一个挑战。本文首次成功地采用一步原位高温磷化法制备了高度分散的非贵金属三金属过度金属磷化Co_0.2Ni_1.6Fe_0.2P助催化剂(PCNS-CoNiFeP)掺杂P的石墨相氮化碳纳米片(PCNS)。有趣的是,PCNS-CoNiFeP与传统氢氧前驱体磷化法制备的CoNiFeP相比,没有聚集性,分散性高。X射线衍射(XRD)、X射线光电子能谱(XPS)、元素映射图像和高分辨率透射电镜(HRTEM)结果表明,PCNS-CoNiFeP已成功合成。紫外-可见吸收光谱结果表明,PCNS-CoNiFeP在200–800 nm波长范围内较PCNS略有增加。光致发光光谱、电化学阻抗谱(EIS)和光电流分析结果表明,CoNiFeP助催化剂能有效促进光生电子-空穴对的分离,加速载流子的迁移。线性扫描伏安法(LSV)结果还表明,负载CoNiFeP助催化剂可大大降低CNS的过电位。结果表明,以三乙醇胺溶液为牺牲剂的PCNS-CoNiFeP最大产氢速率为1200 μmol·h^-1·g^-1,是纯CNS-Pt (320 μmol·h^-1·g^-1)的4倍。在420 nm处的表观量子效率为1.4%。PCNS-CoNiFeP在光催化反应中也表现出良好的稳定性。透射电镜结果表明,6–8 nm的CoNiFeP高度分散在PCNS表面。高度分散的CoNiFeP比聚集的CoNiFeP具有更好的电荷分离能力和更高的电催化析氢活性。由此可见,聚合的CoNiFeP-PCNs (300 μmol·h^-1·g^-1)的产氢速率远低于PCNS-CoNiFeP。此外,CNS的P掺杂可以改善其电导率和电荷传输。     

多壳层中空镍钴双金属磷化物纳米球用于高效电催化析氧北大核心CSCD

析氧反应是金属-空气电池和电解水制氢等电化学系统中关键的反应,研究其高效稳定非贵金属电催化剂至关重要。本文以金属有机骨架化合物(MOF)作为前驱体,通过高温煅烧制备了具有多壳层中空结构的镍钴双金属磷化物(NiCo-P)。这种独特的结构有利于电解液的渗透,能够提供丰富的暴露活性位点和快速传质路径,同时,镍钴双金属具有协同作用促进电化学性能。结果表明,n(Ni)∶n(Co)=1∶10制备的NiCo-P-0.1催化剂在1.0 mol/L KOH电解液中表现出良好的催化活性和稳定性,在10 mA/cm^(2)电流密度的过电势为329 mV,具有良好的应用前景。本工作为高活性和高稳定性的电催化析氧催化剂的制备提供了一种全新途径。     

Ruthenium nanoclusters anchored on cobalt phosphide hollow microspheres by green phosphating process for full water splitting in acidic electrolyte

Transition metal phosphide(TMP) based electrocatalysts possessing special crystal and electronic structures attract broad attention in the field of electrocatalysis.Immense effort is made to optimize TMP catalysts aiming to satisfy the electrochemical catalysis performance.In this work,an environmentally friendly in situ green phosphating strategy and spatial limiting effect of the RuCo precursor is employed to fabricate the ruthenium nanoclusters anchored on cobalt phosphide hollow microspheres(Ru NCs/Co₂P HMs).The obtained Ru NCs/Co₂P HMs electrocatalysts exhibit high hydrogen evolution reaction(HER) activity at wide pH ranges,which require an overpotential of 77 mV to achieve the current density of 10 mA/cm² in 0.5 mol/L H₂SO₄ and 118 mV in 1.0 mol/L KOH.Besides,the multifunctional Ru NCs/Co₂P HMs exhibit good oxygen evolution reaction(OER) activity with an overpotential of 197 mV to reach the current density of 10 mA/cm² in 0.5 mol/L H₂SO₄,which is below that of the commercial RuO₂ electrocatalyst(248 mV).A two-electrode electrolyzer is assembled as well,in acid electrolyte,it achieves a current density of 10 mA/cm² at a voltage of 1.53 V,which is superior to that of the benchmark of precious metal-based electrolyzer(1.58 V).     

Highly Active Electrocatalysis of the Hydrogen Evolution Reaction by Cobalt Phosphide Nanoparticles

Nanoparticles of cobalt phosphide, CoP, have been prepared and evaluated as electrocatalysts for the hydrogen evolution reaction (HER) under strongly acidic conditions (0.50 M H₂SO₄, pH 0.3). Uniform, multi‐faceted CoP nanoparticles were synthesized by reacting Co nanoparticles with trioctylphosphine. Electrodes comprised of CoP nanoparticles on a Ti support (2 mg cm^?2 mass loading) produced a cathodic current density of 20 mA cm^?2 at an overpotential of ?85 mV. The CoP/Ti electrodes were stable over 24 h of sustained hydrogen production in 0.50 M H₂SO₄. The activity was essentially unchanged after 400 cyclic voltammetric sweeps, suggesting long‐term viability under operating conditions. CoP is therefore amongst the most active, acid‐stable, earth‐abundant HER electrocatalysts reported to date.     

中空核壳结构Ni1.2Co0.8P@N-C钠离子电池负极材料的制备及拉曼研究

本文设计制备了一种新型的氮掺杂碳包覆镍钴双金属磷化物中空核壳结构纳米立方体(Ni_1.2Co_0.8P@N-C)作为钠离子电池负极材料. 该材料以镍钴类普鲁士蓝(PBA)纳米粒子为模板,先后经水热法、磷化法和高温碳化处理后合成. 将其作为活性材料应用在钠离子电池中,该材料展现出优异的循环稳定性,当以100 mA·g^-1的电流密度循环至200圈时,该材料的库仑效率保持在99.3%. 进一步通过对不同电位下Ni_1.2Co_0.8P@N-C材料中的氮掺杂碳进行原位拉曼光谱测试,结果显示钠离子在氮掺杂的碳壳中的脱嵌行为具有较大程度的可逆性,研究结果对钠离子电池充放电过程的后续电化学研究提供了有价值的信息.     

ZIF-67 derived carbon wrapped discontinuous CoxP nanotube as anode material in high-performance Li-ion battery

Transition metal phosphides (TMPs) are prospective anode materials for lithium-ion batteries (LIBs) due to their high theoretical capacities and low redox voltages. Herein, we report a template directing method to develop a tube-sheath hybrid composing of cobalt phosphide particles encapsulated in metal organic frameworks (MOFs) derived N-doped carbon sheaths (Co_xP@NC). The utilization of directing template leads to a homogenous distribution of the subsequently formed cobalt phosphide particles, restrains the aggregation of cobalt phosphides, and thus results in the superb rate capability and cyclability. Contributable to the integrated merits of the interior downsized cobalt phosphide particles and the outer ZIF-67 derived porous carbon sheath, the volume expansion during cycling is effectively suppressed. The Co_xP@NC hybrid shows superb electrochemical performance as anode material for LIB, with good reversible capacity of 928 mAh·g^?1 after 100 cycles at 0.1 A g^?1, and high stability of 526 mAh·g^?1 after 600 cycles at 1.0 A g^?1. This work provides a route for rational design of MOF derived carbon-based anode material for LIB, which could also be applied as a promising platform in diverse field.     

Atomic Layer Deposition of Cobalt Phosphide for Efficient Water Splitting

Transition‐metal phosphides (TMP) prepared by atomic layer deposition (ALD) are reported for the first time. Ultrathin Co‐P films were deposited by using PH₃ plasma as the phosphorus source and an extra H₂ plasma step to remove excess P in the growing films. The optimized ALD process proceeded by self‐limited layer‐by‐layer growth, and the deposited Co‐P films were highly pure and smooth. The Co‐P films deposited via ALD exhibited better electrochemical and photoelectrochemical hydrogen evolution reaction (HER) activities than similar Co‐P films prepared by the traditional post‐phosphorization method. Moreover, the deposition of ultrathin Co‐P films on periodic trenches was demonstrated, which highlights the broad and promising potential application of this ALD process for a conformal coating of TMP films on complex three‐dimensional (3D) architectures.