表面富集的超小铂纳米颗粒耦合缺陷磷化钴用于高效的电催化水分解和柔性锌空气电池

开发多功能的纳米电催化剂可以提高单位催化剂表面活性密度.本课题组采用热解和还原工艺制备了具有多功能电催化性能的超小铂纳米颗粒耦合缺陷CoP的纳米材料(Pt/d-CoP/NPC),它具有较高的氧还原反应(ORR)半波电位(0.82 V).所合成的Pt/d-CoP/NPC电催化剂具有良好的电催化析氢反应活性,当反应活性达到10 mA cm^(-2)时,过电位分别为33 mV@1mol/L KOH, 10 mV@0.5 mol/L H_(2)SO_(4)和70 mV@1 mol/L PBS.Pt/d-CoP/NPC催化剂还表现出较好的析氧反应活性.以合成的催化剂Pt/d-CoP/NPC作为电极组装的全解水装置和可充电锌空气电池具有良好的活性和稳定性,可以持续有效地驱动全解水产氢,在存储可再生能源方面的具有较好的应用潜力.采用X射线光电子能谱(XPS)、拉曼光谱测试和傅里叶红外光谱测试(FTIR)等技术研究了Pt颗粒与CoP之间的相互作用,并利用密度泛函理论(DFT)计算研究了催化剂的ORR反应机制.Pt/d-CoP/NPC在129.3 (2p_(3/2))和130.1 eV (2p_(1/2))处的P 2p轨道观察到P-M键,证实了金属磷化物的存在.Pt/d-CoP/NPC的Co结合能相对于d-CoP/NPC的结合能发生了正移,表明Pt与CoP之间存在电子相互作用.由于Co和Pt的电负性差异,Pt/d-CoP/NPC中Pt的峰值与商用Pt/C相比呈负移,说明电子从Co向Pt转移.XPS也证实了碳的存在.此外,拉曼光谱也出现了碳的特征峰D峰和G峰.并且Pt/d-CoP/NPC和d-CoP/NPC的ID/IG值相似,说明Pt的引入不会影响碳基体的结构.在N 1s光谱中,检测到N-P和吡啶氮的存在,证实在Pt/d-CoP/NPC和d-CoP/NPC中形成了N, P掺杂的碳.此外, Pt/d-CoP/NPC的FTIR谱出现对应于P-O, N-P, C-C, C-H和O-H的峰,也证明了氮磷共掺杂碳的存在.通过DFT计算进一步分析Pt/d-CoP/NPC电催化剂具有良好ORR活性的原因.结果表明,电荷从CoP转移到Pt,有利于活性氧分子的活化,促进催化过程.对比不同模型ORR过程中间体的自由能图, Pt/d-CoP/NPC和Pt/C的速率决定步骤为O_(2)生成OOH^(*),合成的Pt/d-CoP/NPC具有有利的热力学过电位,证明了其高效的ORR性能.此外, Pt/d-CoP/NPC中Pt的d带中心相对于纯Pt有明显的正向费米能级转移,说明引入的CoP可以导致离域电子重分布,从而优化了反应中间体的吸附.综上,Pt/d-CoP/NPC催化剂中Pt与CoP之间存在相互作用,进而提高催化活性,该催化剂的合成有望为开发多功能电催化纳米材料提供参考.

Co-Ru alloy nanoparticles decorated onto two-dimensional nitrogen doped carbon nanosheets towards hydrogen/oxygen evolution reaction and oxygen reduction reaction

Constructing highly-efficient electrocatalysts toward hydrogen evolution reaction(HER)/oxygen evolution reaction(OER)/oxygen reduction reaction(ORR)with excellent stability is quite important for the development of renewable energy-related applications.Herein,Co-Ru based compounds supported on nitrogen doped two-dimensional(2D)carbon nanosheets(NCN)are developed via one step pyrolysis procedure(Co-Ru/NCN)for HER/ORR and following low-temperature oxidation process(Co-Ru@RuO_(x)/NCN)for OER.The specific 2D morphology guarantees abundant active sites exposure.Furthermore,the synergistic effects arising from the interaction between Co and Ru are crucial in enhancing the catalytic performance.Thus,the resulting Co-Ru/NCN shows remarkable electrocatalytic performance for HER(70 mV at 10 mA cm^(-2))in 1 M KOH and ORR(half-wave potential E_(1/2)=0.81 V)in 0.1 M KOH.Especially,the Co-Ru@RuO_(x)/NCN obtained by oxidation exhibits splendid OER performance in both acid(230 mV at 10 mA cm^(-2))and alkaline media(270 mV at 10 mA cm^(-2))coupled with excellent stability.Consequently,the fabricated two-electrode water-splitting device exhibits excellent performance in both acidic and alkaline environments.This research provides a promising avenue for the advancement of multifunctional nanomaterials.

优化金属磷化物电催化析氢性能的策略

日益严重的能源危机和环境污染问题使得探索清洁的可再生能源载体及减少对传统化石燃料的过度依赖成为人们面临的一项重要任务.因此,各种可持续能源如太阳能、风能、海洋能和生物质能等得到了广泛研究并取得了一定的进展.然而,这些能源因存在间歇性和不稳定性等缺点阻碍了其实际应用.近年,氢气作为一种能源载体,以其高能量密度和无碳排放的优点引起了人们的广泛关注,被认为是缓解日益严重的污染问题的最有前途的环保能源.对比目前采用的天然气热解和煤炭气化等传统制氢策略,电催化水裂解由于催化效率高,制氢纯度高和不产生温室气体,被认为是高效、环保、可持续的制氢策略.电催化水裂解由两个独立的半反应组成,分别是析氢反应和析氧反应.析氢反应作为水裂解的一个半反应,在降低制氢成本及提高产氢催化效率方面起着关键作用.然而,目前的核心问题之一是要开发高效的析氢电催化剂,以加快反应速度.目前,铂和铂基纳米材料被认为是高效的析氢电催化剂,但是其稀缺性和高成本阻碍了大规模实际应用.金属磷化物由于具有较高的本征活性并且在不同的电解质中都具有良好的电催化析氢性能,被证明是一种优良的析氢电催化剂.此外,与普通催化剂相比,金属磷化电催化剂还具有合成简便、效率高、成本低、省时等优点.本文详细介绍了近年人们在金属磷化物用于电催化析氢研究中取得的进展.首先,介绍了电催化析氢反应机理,金属磷化物的结构及作用,并对其优缺点进行了总结;随后,综述了金属磷化物的合成方法,包括后处理、原位生成和电沉积策略,并对不同方法进行了比较和讨论.此外,从元素掺杂、界面工程、空穴工程、修饰特定载体、构建特定纳米结构、设计双或多金属磷化物和其他发展的新方法等七个方面详细总结了促进金属磷化物电催化活性的多种策略,并进行了对比和讨论.最后,归纳了金属磷化物在电催化析氢应用中存在的问题和面临的挑战,并对未来的研究发展提出了展望.

Surface/Interface Engineering of Hierarchical MoO_(2)/MoNi_(4)@Ru/RuO_(2)Heterogeneous Nanosheet Arrays for Alkaline Water Electrolysis with Fast Kinetics

Realizing the hydrogen economy by water electrolysis is an attractive approach for hydrogen production,while the efficient and stable bifunctional catalysts under high current densities are the bottleneck that limits the half-cell reactions of water splitting.Here,we propose an approach of hydrothermal and thermal annealing methods for robust MoO_(2)/MoNi_(4)@Ru/RuO_(2) heterogeneous cuboid array electrocatalyst with multiplying surface-active sites by depositing a monolayer amount of Ru.Benefiting from abundant MoO_(2)/MoNi_(4)@Ru/RuO_(2)heterointerfaces,MoO_(2)/MoNi_(4)@Ru/RuO_(2) heterogeneous cuboid array electrocatalysts effectively drive the alkaline water splitting with superior hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)performances.The synthesized MoO_(2)/MoNi_(4)@Ru/RuO_(2) has high HER activity,which realizes the working overpotentials of 48 mV at 50 mA·cm^(-2),further achieving overpotentials of 230 mv for industry-level 1000 mA·cm^(-2) in alkaline water electrolysis.Moreover,it also showed an enhanced OER activity than commercial RuO_(2) with a small overpotential of 280 mV at 200 mA·cm^(-2) in alkaline media.When building an electrolyzer with electrodes of(-)MoO_(2)/MoNi_(4)@Ru/RuO_(2)IIMo02/MoNig@Ru/RuO_(2)(+),a cell voltage of 1.63 V and 1.75 V is just required to support the current density of 200 mA·cm^(-2) and 500 mA-cm^(-2) in alkaline water electrolysis,much lower than that of the electrolyzer of(-)Pt/CIIRuO_(2)(+).This work demonstrates that MoO_(2)/MoNig@Ru/RuO_(2) heterogeneous nanosheet arrays are promising candidates for industrial water electrolysis applications,providing a possibility for the exploration of water electrolysis with a large currentdensity.

Amorphous NiO_(n)coupled with trace PtO_(x)toward superior electrocatalytic overall water splitting in alkaline seawater media

Developing corrosion resistance bifunctional electrocatalysts with high activity and stability toward both hydrogen evolution reaction(HER)and oxygen evolution reaction(OER),especially electrolysis in seawater,is of prime significance but still pressingly challenging.Herein,in-situ introduced PtO_(x)on the derivative amorphous NiO_(n)is prepared via heat treatment of Ni ZIFL nanosheets on nickel foam under low temperature(PtO_(x)-NiO_(n)/NF).The synthesized PtO_(x)-NiO_(n)/NF possesses suprahydrophilic and aerophilic surface,then in favor of intimate contact between the electrode and electrolyte and release of the generated gas bubbles during the electrocatalysis.As a result,the in-situ PtO_(x)-NiO_(n)/NF electrode presents outstanding bifunctional activity,which only requires extremely low overpotentials of 32 and 240 mV to reach a current density of 10 mA·cm^(-2)for HER and OER,respectively,which exceeds most of the electrocatalysts previously developed and even suppresses commercial Pt/C and RuO_(2)electrodes.As for two-electrode cell organized by PtO_(x)-NiO_(n)/NF,the voltages down to 1.57 and 1.58 V are necessary to drive 10 mA·cm^(-2)with remarkable durability in 1 M KOH and alkaline seawater,respectively,along with remarkable stability.Moreover,a low cell voltage of 1.88 V is needed to achieve 1,000 mA·cm^(-2)toward water-splitting under industrial conditions.This study provides a new idea for designing in-situ amorphous metal oxide bifunctional electrocatalyst with strong Pt–support interaction for overall water splitting.

Porous needle-like Fe-Ni-P doped with Ru as efficient electrocatalyst for hydrogen generation powered by sustainable energies

Electrocatalytic water electrolysis,involving hydrogen evolution reaction(HER)and oxygen evolution reaction(OER),two halfreactions,is an eco-friendly approach toward hydrogen production.In this work,needle-like Ru-Fe-Ni-P on NiFe foam is prepared through corrosive engineering and following a low-temperature phosphorization procedure for overall water-splitting.The as-designed Ru-Fe-Ni-P exhibits a porous needle-like structure,surface,and binder-free merits,and then can expose rich active sites,favor the transportation of mass/electron,and accelerate the reaction kinetics during catalytic process.Then,the synthesized Ru-Fe-Ni-P owns remarkable catalytic performance for HER,with 18 and 67 mV to reach 10 mA·cm^(−2)in alkaline and neutral media.Moreover,a low cell voltage of 1.51 V is required to produce a current of 10 mA·cm^(−2)in a two electrode electrolyzer with excellent stability.Interestingly,sustainable energies can power the electrolyzer effectively with abundant hydrogen generation.

封装有Ni掺杂FeP纳米颗粒的氮掺杂碳纳米管作为双功能电催化剂

清洁能源支撑的电解海水技术是公认的最有前途的未来可持续绿色制氢途径.商用贵金属催化剂储量低、成本昂贵,且在复杂离子环境下容易快速失活的特性,严重阻碍了电解海水技术的工业化发展.本工作通过Ni掺杂Fe团簇催化碳纳米管生长,再气体磷化法,成功构建了一种含Ni掺杂FeP纳米颗粒封端的新型氮掺杂碳纳米管交织结构(NFP@NC).独特的N-CNTs交织网络,以及N-CNTs和Ni掺杂FeP的强相互作用提供了快速的传质途径,提高了气体逸出效率,并显著增强了催化剂稳定性.NFP@NC在10 mA cm^(−2)的电流密度下的析氧反应过电位为280 mV,析氢反应过电位为206 mV,低于大多数报道的铁基催化剂.本研究为构建交织的碳纳米管网络和制备高性能双功能海水电解催化剂提供了一种有效的途径.

Highly nitrogen and sulfur dual-doped carbon microspheres for supercapacitors

Heteroatom doping, especially dual-doped carbon materials have attracted much attention for the past few years, and have been regarded as one of the most efficient strategies to enhance the capacitance behavior of porous carbon materials. In this work, a facile two-step synthetic route was developed to fabricate nitrogen and sulfur co-doped carbon microsphere(NSCM) by using thiourea as dopant. The N/S doping content is controlled via varying the carbonization temperature. It has been proved that a suitable quantity of N and S groups could not only provide pseudo-capacitance but also promote the electron transfer for carbon materials, which ensures the further utilization of the exposed surfaces for charge storage. The optimized NSCM prepared at a carbonization temperature of 800 °C(NSCM-800) achieves a capacitance of 277.1 Fg^(-1)at a current density of 0.3 Ag^(-1)in 6.0 mol L^(-1)KOH electrolyte, which is71% higher than that of undoped carbon microsphere. Besides, NSCM-800 shows an excellent cycling stability, 98.2% of the initial capacitance is retained after 5,000 cycles at a current density of 3.0 Ag^(-1).

Biomass derived nitrogen doped carbon with porous architecture as efficient electrode materials for supercapacitors

Developing porous carbon materials with low-cost, sustainable and eco-friendly natural resources is emerging as an ever important research field in the application of high-performance supercapacitor. In this paper, a simple synthetic method to fabricate nitrogen doped porous carbon （NPC） is developed via a one-pot carbonization of sodium alginate and urea. The as-prepared NPC annealed at 700℃ with meso- and macro-porous structure exhibits excellent specific capacitance （180.2 F/g at 1 A/g） and superior cycling life when serves as electrode materials for supercapacitor. Moreover, the investigation on the annealing temperature demonstrates that NPC pyrolysis at 700℃ possesses relatively high pyrrole nitrogen and pyridine nitrogen, which is favorable for enhancing supercapacitor performance. This work extends biomass derived carbon materials in energy storage applications.

腐蚀-配位工程构建含有微量Pt的2D-3D纳米结构高效电解水催化剂

开发具有良好的催化性能和稳定性的析氢反应(HER)和析氧反应(OER)的电催化剂对水分解产氢的商业化起着关键作用.本文通过简单、可扩展的腐蚀配位方法,将金属氢氧化物和金属有机骨架(MOF)组成的二维-三维(2D-3D)纳米结构原位装饰在泡沫Ni Fe (Pt-Ni Fe PBA)上.所设计的特殊形态有利于在电催化过程中提供丰富的活性位点、优化反应途径和加速传质.因此,合成的Pt-Ni Fe PBA在1 mol L;KOH中HER和OER在10 m A cm^(-2)时具有29和210 m V的过电位.值得注意的是,在10 m A cm^(-2)时该催化剂仅需21 m V即可驱动1 mol L;KOH海水,并具有出色的稳定性.此外,将合成的Pt-Ni Fe PBA用作双功能电催化剂时,只需1.46和1.48 V即可以达到10 m A cm^(-2).此外,间歇性的可持续能源,如热能、风能和太阳能可以为该水分解器提供动力.