Electrochemical water splitting is a clean technology that can store the intermittent renewable wind and solar energy in H2 fuels. However, large-scale H2 production is greatly hindered by the sluggish oxygen evolution reaction (OER) kinetics at the anode of a water electrolyzer. Although many OER electrocatalysts have been developed to negotiate this difficult reaction, substantial progresses in the design of cheap, robust, and efficient catalysts are still required and have been considered a huge challenge. Herein, we report the simple synthesis and use of α-Ni(OH)2 nanocrystals as a remarkably active and stable OER catalyst in alkaline media. We found the highly nanostructured α-Ni(OH)2 catalyst afforded a current density of 10 mA cm(-2) at a small overpotential of a mere 0.331 V and a small Tafel slope of ~42 mV/decade, comparing favorably with the state-of-the-art RuO2 catalyst. This α-Ni(OH)2 catalyst also presents outstanding durability under harsh OER cycling conditions, and its stability is much better than that of RuO2. Additionally, by comparing the performance of α-Ni(OH)2 with two kinds of β-Ni(OH)2, all synthesized in the same system, we experimentally demonstrate that α-Ni(OH)2 effects more efficient OER catalysis. These results suggest the possibility for the development of effective and robust OER electrocatalysts by using cheap and easily prepared α-Ni(OH)2 to replace the expensive commercial catalysts such as RuO2 or IrO2.

Advanced energy conversion and storage (ECS) devices (including fuel cells, photoelectrochemical water splitting cells, solar cells, Li-ion batteries and supercapacitors) are expected to play a major role in the development of sustainable technologies that alleviate the energy and environmental challenges we are currently facing. The successful utilization of ECS devices depends critically on synthesizing new nanomaterials with merits of low cost, high efficiency, and outstanding properties. Recent progress has demonstrated that nanostructured metal chalcogenides (MCs) are very promising candidates for efficient ECS systems based on their unique physical and chemical properties, such as conductivity, mechanical and thermal stability and cyclability. In this review, we aim to provide a summary on the liquid-phase synthesis, modifications, and energy-related applications of nanostructured metal chalcogenide (MC) materials. The liquid-phase syntheses of various MC nanomaterials are primarily categorized with the preparation method (mainly 15 kinds of methods). To obtain optimized, enhanced or even new properties, the nanostructured MC materials can be modified by other functional nanomaterials such as carbon-based materials, noble metals, metal oxides, or MCs themselves. Thus, this review will then be focused on the recent strategies used to realize the modifications of MC nanomaterials. After that, the ECS applications of the MC/modified-MC nanomaterials have been systematically summarized based on a great number of successful cases. Moreover, remarks on the challenges and perspectives for future MC research are proposed (403 references).

The electroreduction of water for sustainable hydrogen production is a critical component of several developing clean-energy technologies, such as water splitting and fuel cells. However, finding a cheap and efficient alternative catalyst to replace currently used platinum-based catalysts is still a prerequisite for the commercialization of these technologies. Here we report a robust and highly active catalyst for hydrogen evolution reaction that is constructed by in situ growth of molybdenum disulfide on the surface of cobalt diselenide. In acidic media, the molybdenum disulfide/cobalt diselenide catalyst exhibits fast hydrogen evolution kinetics with onset potential of −11 mV and Tafel slope of 36 mV per decade, which is the best among the non-noble metal hydrogen evolution catalysts and even approaches to the commercial platinum/carbon catalyst. The high hydrogen evolution activity of molybdenum disulfide/cobalt diselenide hybrid is likely due to the electrocatalytic synergistic effects between hydrogen evolution-active molybdenum disulfide and cobalt diselenide materials and the much increased catalytic sites.

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Two-dimensional g-C3N4 nanosheets with few-layer thickness, ensuring equivalent charge migrations to various Pd facets, provide an ideal model system for reliably examining the facet selectivity of Pd co-catalysts. It reveals that reduction of CO2 can occur better on Pd{111} facets while H2O prefers to generate H2 on Pd{100}.

MoSe2 nanosheets have been extensively pursued due to the outstanding properties of this typical layered transition metal dichalcogenide (LTMD). In this work, we report a facile, fast strategy to synthesize scalable hierarchical ultrathin MoSe2-x (x ∼ 0.47) nanosheets. The nanosheets possess 2-5 Se-Mo-Se atomic layers and were synthesised through a bottom-up colloidal route within 20 mins under mild conditions from the reaction of MoO2(acac)2 with dibenzyl diselenide. The as-obtained hierarchical ultrathin MoSe2-x nanosheets are Mo-rich with a Se vacancy and show excellent HER performance with a small overpotential of ∼170 mV, large cathodic currents, and a Tafel slope of 98 mV per decade. Such high performance has been attributed to the unique structure of the Se vacancy defect, large surface area, as well as the enhanced conductivity. Meanwhile, the pathway can be extended as a general strategy to prepare other metal selenides, such as ultrathin WSe2 and SnSe nanosheets, and PbSe nanocrystals. It will also pave a new way to synthesize scalable nanostructured materials for intriguing nanodevices and large-scale applications.

Uniform and monodisperse CuO nanorods have been synthesized by directional aggregation and crystallization of tiny CuO nanoparticles generated from a solid-liquid arc discharge process under ambient conditions in the absence of any surfactants. Uniform CuO nanorods with sharp ends are formed from tiny nanoparticles via a process that involves the rapid oxidation of Cu nanoclusters, the spontaneous aggregation of CuO nanoparticles, and the Ostawald ripening process. The spontaneous aggregation and oriented attachment of tiny CuO nanoparticles contributed obviously to the formation of these kinds of nanostructures. By choice of suitable reducing agent to prevent the oxidation of Cu nanoclusters, Cu and Cu2O nanoparticles can be selectively synthesized.

ideal performance toward ORR or OER, the high price, scarcity, and instability still hampers their large-scale generalization. At present, developing efficient and nonnoble-metal catalysts has attracted extensive interest. [11][12][13][14][15][16][17][18] For ORR, defective carbon-based materials, typically heteroatom-doped carbon, are extensively demonstrated as efficient electrocatalysts. [19][20][21][22] For OER, in addition to common transition metal oxides or (oxy)hydroxides, transition metal phosphides (TMPs) have achieved considerable research and development attention due to superior performance. [23][24][25][26][27] In this regard, the composites of the TMPs and defective carbon are considered as promising candidates for both ORR and OER. More recently, some works reported that the composites of the TMPs and defective carbon compared to the single component displayed enhanced catalytic performance, which was probably attributed to the increased electronic conductivity due to the introduction of conductive carbon. [28][29][30] However, the promoting factor was not well understood. For the composites, undoubtedly, the interfacial properties, especially the interfacial charge states, are important parameters that could influence the catalytic performance. [31,32] Therefore, in order to overcome high catalytic reaction barrier, designing the hybrids of the TMPs and defective carbon and probing the interfacial charge distribution behavior are highly desirable to realize bifunctional oxygen electrocatalysis.Herein, we constructed a new type of hybrids of the CoP and defective carbon (marked as CoP-DC). We revealed the interfacial charge transfer process of the hybrids by multiple synchrotron-based X-ray absorption structure, ultraviolet photoelectron spectra (UPS), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations. The interfacial charge redistribution was observed, which subsequently contributed to enhanced ORR activity on the defective carbon and enhanced OER activity on the CoP.The CoP-DC hybrids were synthesized through a simple phosphorization reaction toward the Co 2+ -contained polymer hydrogel. Typically, the polymer hydrogel was obtained by inserting Co 2+ into polymer hydrogel framework under alkaline condition according to previous reports, and then was phosphorized The development of efficient catalysts for both oxygen reduction and evolution reactions (oxygen reduction reaction (ORR) and oxygen evolution reaction (OER)) is central to regenerative fuel cells and rechargeable metalair batteries. It is highly desirable to achieve the efficient integration of dual active components into the catalysts and to understand the interaction between the dual components. Here, a facile approach is demonstrated to construct defective carbon-CoP nanoparticle hybrids as bifunctional oxygen electrocatalysts, and further probe the interfacial charge distribution behavior. By combining multiple synchrotron-based X-ray spectroscopic characterizations with density functional theo...