一步硫/磷热处理制备空心Co9S8/CoP/C纳米复合材料及其储钠性能研究

低成本、高性能的钠离子电池有望成为代替锂离子电池的下一代核心器件.但是开发出高比容量、高倍率的钠离子电池负极材料依然是瓶颈.本文通过水热/溶剂热法制备了Co基前驱体,然后将其一步硫/磷热处理制得具有空心多孔结构的h-Co₉S₈/CoP/C纳米复合材料.通过X-射线粉末衍射(XRD)、拉曼光谱(Raman)、扫描电镜(SEM)、透射电镜(TEM)和X-射线光电子能谱(XPS)等表征以确定纳米复合物的物相以及形貌特征.当h-Co₉S₈/CoP/C作为钠离子电池负极材料时,该电极材料展示了高的比容量(561 mAh g^-1@0.1 Ag^-1)、较好的循环性能(可逆比容量200 mAh g^-1@2 Ag^-1)和倍率性能.h-Co₉S₈/CoP/C之所以显示出良好的储钠性能,主要得益于其空心多孔结构不仅提供更多的空间缓解钠在反复嵌入和脱出过程造成的体积膨胀效应,而且可以缩短离子/电荷扩散途径以加快反应动力学,此外,Co₉S₈、CoP和C独特的电子结构优势得以共同发挥.     

电化学合成CoP-Cu复合丝及其巨磁阻抗效应

电化学合成CoP-Cu复合丝及其巨磁阻抗效应;钴磷非晶合金;电沉积;巨磁阻抗;复合丝     

Needle-like cobalt phosphide arrays grown on carbon fiber cloth as a binder-free electrode with enhanced lithium storage performance

Cobalt phosphide(CoP) is a promising anode candidate for lithium-ion batteries(LIBs) due to its high specific capacity and low working potential.However,the poor cycling stability and rate performance,caused by low electrical conductivity and huge volume variation,impede the further practical application of CoP anode materials.Herein,we report an integrated binder-free electrode featuring needle-like CoP arrays grown on carbon fiber cloth(CC) for efficient lithium storage.The as-prepared CoP/CC electrode integrates the advantages of 1 D needle-like CoP arrays for efficient electrolyte wettability and fast cha rge transpo rtation,and 3 D CC substrate for superior mechanical stability,flexibility and high conductivity.As a result,the CoP/CC electrode delivers an initial specific capacity of 1283 mAh/g and initial Coulombic effeciencies of 85.4%,which are much higher than that of conventional CoP electrode.Notably,the Co P/CC electrode shows outstanding cycling performance up to 400 cycles at 0.5 A/cm² and excellent rate performance with a discharge capacity of 549 mAh/g even at 5 A/cm².This work demonstrates the great potential of integrated CoP/CC hybrid as efficient bind-free and freestanding electrode for LIBs and future flexible electronic devices.     

化学镀法制备CoP量子点修饰g-C3N4用于光催化产氢（英文）

光催化分解水制氢被认为是解决当前能源危机和环境污染问题的重要途径之一.在众多光催化剂中,石墨相氮化碳(g-C3N4)因其具有高的热稳定性、高的化学稳定性、合适的能带位置以及成本低廉等优点,受到光催化领域研究者的广泛关注,成为研究热点.然而,由于g-C3N4的禁带宽度较大(Eg=2.7 eV),导致其对可见光的响应较差,而且光生电子-空穴对在其中易于复合,从而导致其光催化产氢活性较低.已有研究表明,助催化剂可以有效地促进催化剂中光生载流子的分离和传输,从而提高光催化剂的光催化活性和氢气的产生速率.目前使用最广泛的助催化剂多为贵金属(Au,Ag,Pt和Pd等),然而贵金属储量低、成本高,极大地限制了其实际应用.因而,开发适用于光催化水分解制氢的非贵金属助催化剂成为该领域的研究热点.其中,用非贵金属助催化剂修饰g-C3N4制备高效光催化剂分解水制氢技术引起了人们极大的兴趣.过渡金属磷化物(FeP,CoP,CuP,NiP等)是一种有效的光催化辅助催化剂.然而,这些金属磷化物的合成通常使用有毒的有机磷化合物和白磷或涉高温煅烧.特别是在传统水热法制备金属磷化物过程中会释放大量氢气,导致容器内压力过高,造成较大的安全问题.据报道,在这些磷化物中,磷化钴由于其合适的能带结构和较高的导电性,作为光催化分解水助催化剂受到了广泛关注.然而,截至目前,关于磷化钴作为助催化剂用于光催化的实用技术报道很少,特别是在温和条件下制备磷化钴修饰的g-C3N4复合光催化剂的研究还有待进行.本文研究了以CoP作为助催化剂来改进g-C3N4(制备g-C3N4/CoP),并用于光催化水裂解制氢气.复合光催化剂g-C3N4/CoP经由两步反应合成.第一步采用尿素热分解法制备g-C3N4,第二步通过化学镀法将CoP修饰在g-C3N4表面.采用XRD,TEM,UV-DRS和XPS等手段表征了g-C3N4/CoP光催剂的性质.结果表明,CoP以量子点(QDs)形式均匀分布在g-C3N4表面,显著提高了g-C3N4的光催化活性.不同CoP负载量的样品中,g-C3N4/CoP-4%表现出优异的光催化活性,H2生成速率为936μmol g^-1 h^-1,甚至高于4%Pt负载的g-C3N4(H2的生成速率仅为665μmol g^-1 h^-1).从紫外可见光谱上看,g-C3N4在451 nm达到吸收波长上限,但与CoP复合后,g-C3N4/CoP-4%的吸收波长上限延展到497 nm.此外,光致发光和光电流测试结果证实,将CoP量子点负载到g-C3N4上不仅可以降低光生电荷-空穴对的复合,而且可以改善光生e--h+对的转移,从而提高光催化剂的产氢性能.这项工作为开发高效的非贵金属助催化剂修饰g-C3N4的技术提供了一个可行策略,所制材料在光催化制氢领域显示出潜在的应用前景.     

Phosphating-induced charge transfer on CoO/CoP interface for alkaline H2 evolution

Designing non-noble metal electrocatalysts toward alkaline hydrogen evolution reaction (HER) with high performance at a large current density is urgent. Herein, a CoO/CoP heterostructure catalyst (termed POZ) was designed by a phosphating strategy. The strong electron transfer on the interface of CoO/CoP was experimentally and theoretically proven. POZ showed a low overpotential of 236 mV at 400 mA/cm², which was 249 mV lower than non-phosphated sample. It also exhibited a remarkable solar-to-hydrogen conversion efficiency of 10.5%. In this work, the construction of CoO/CoP interface realized by a simple phosphating strategy could provide an important reference to boost the HER performance on those materials not merely metal oxides.     

Cobalt Phosphide Nanowires: Efficient Nanostructures for Fluorescence Sensing of Biomolecules and Photocatalytic Evolution of Dihydrogen from Water under Visible Light

The detection of specific DNA sequences plays an important role in the identification of disease‐causing pathogens and genetic diseases, and photochemical water splitting offers a promising avenue to sustainable, environmentally friendly hydrogen production. Cobalt–phosphorus nanowires (CoP NWs) show a high fluorescence quenching ability and different affinity toward single‐ versus double‐stranded DNA. Based on this result, the utilization of CoP NWs as fluorescent DNA nanosensors with a detection limit of 100 pM and a selectivity down to single‐base mismatch was demonstrated. The use of a thrombin‐specific DNA aptamer also enabled the selective detection of thrombin. The photoinduced electron transfer from the excited dye that labels the oligonucleotide probe to the CoP semiconductor led to efficient fluorescence quenching, and largely enhanced the photocatalytic evolution of hydrogen from water under visible light.     

基于CoP纳米笼的高效无酶葡萄糖电化学传感器

采用水热法和煅烧结合的方法制备过渡金属磷化钴(CoP)纳米笼,并利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、扫描透射电子显微镜(STEM)、X射线衍射(XRD)和X射线光电子能谱(XPS)表征CoP的形貌、结构和元素组成。研究发现,所合成的CoP具有中空纳米笼的结构,该结构有利于提供更多可接触的催化活性位点,促进电子或离子的传输,加快催化反应过程。采用循环伏安法(CV)和计时电流法研究表明CoP纳米笼对葡萄糖具有优异的电催化氧化活性。基于CoP纳米笼修饰的玻碳电极构建的无酶葡萄糖电化学传感器显示出优异的性能。该传感器具有宽的线性范围(0.04～3 mmol·L-1和3～8 mmol·L-1)、低的检测限(3.8μmol·L-1)和高的灵敏度,以及良好的选择性、重复性、重现性和稳定性。另外,该传感器能够实现人体血清中葡萄糖的快速检测。     

基于CoP纳米阵列的亚硝酸根传感器的研究

亚硝酸盐对环境和人体健康有着不利的影响,人体长期食用含大量亚硝酸盐的食物有致癌的风险,对亚硝酸盐的分析和检测是非常重要的. 开发高效的电催化剂,从而实现高灵敏度和高选择性的亚硝酸盐检测具有十分重要的意义. 作者通过先水热再低温磷化获得了磷化钴纳米阵列（CoP/TM）.电化学测试结果表明,所构建的CoP/TM电极对亚硝酸盐的还原具有高效的催化作用,线性检测范围为1.0 μmol·L^-1到1.0 mmol·L^-1,检测下限为18 nmol·L^-1（S/N=3）,响应灵敏度为17781 μA·(mmol·L^-1)^-1·cm^-2,响应时间小于3 s,选择性良好.     

MOF-derived Core-Shell CoP@NC@TiO2 Composite as a High-Performance Anode Material for Li-ion Batteries

Transition-metal phosphides have been regarded as promising anode materials for high-energy lithium-ion batteries (LIBs) due to their high capacity and low cost. However, the mechanical pulverization and resultant capacity fade critically limit their further development. Here, we have designed an innovative core-shell CoP@NC@TiO₂ composite with an exotic rhombic dodecahedral morphology derived from ZIF-67 precursor, which combines both advantages from TiO₂ with excellent cycling stability and CoP with high capacity. The additional MOF-derived N-doped carbon framework is considered to improve the electrical conductivity and accommodate the volume expansion of CoP particles. Moreover, the outer TiO₂ shell can also buffer the mechanical stress and maintain the integrity of composite. With the unique structure, the core-shell CoP@NC@TiO₂ composite material exhibits excellent electrochemical performance with a considerable discharge specific capacity of 706.3 mAh g⁻¹ at a current density of 100 mA g⁻¹ after 200 cycles and outstanding rate capacity. Hence, our work demonstrates that this core-shell structure strategy combined with MOF-derived carbon framework could provide a practical pathway towards enhanced electrode materials for energy storage and conversion.     

Heteroatom Doping Promoting CoP for Driving Water Splitting

CoP nanomaterials have been extensively regarded as one of the most promising electrocatalysts for overall water splitting due to their unique bifunctionality. Although the great promise for future applications, some important issues should also be addressed. Heteroatom doping has been widely acknowledged as a potential strategy for improving the electrocatalytic performance of CoP and narrowing the gap between experimental study and industrial applications. Recent years have witnessed the rapid development of heteroatom-doped CoP electrocatalysts for water splitting. Aiming to provide guidance for the future development of more effective CoP-based electrocatalysts, we herein organize a comprehensive review of this interesting field, with the special focus on the effects of heteroatom doping on the catalytic performance of CoP. Additionally, many heteroatom-doped CoP electrocatalysts for water splitting are also discussed, and the structure-activity relationship is also manifested. Finally, a systematic conclusion and outlook is well organized to provide direction for the future development of this interesting field.