7337wileyonlinelibrary.com energy and the development of regenerative fuel cells and rechargeable metal-air batteries. [1][2][3][4] Note that overpotentials originating from the polarization phenomenon occurring at the electrodes induce a larger voltage window than the theoretical minimum one (1.23 V) to afford thermodynamic driving force. [ 5,6 ] As such, the sluggish apparent reaction kinetics necessitates the utilization of noble-metal-based electrocatalysts to achieve respectable performance, i.e., Pt for HER and IrO 2 / RuO 2 for OER, [ 7,8 ] though the scarcity and the consequent unfavorable cost prohibit the scale-up deployment in energy devices. Accordingly, great efforts have been made toward effi cient earth-enriched materials, such as OER catalysts working under strongly alkaline conditions and HER catalysts operating in strongly acidic mediums, due to the thermodynamic convenience and application prospect in alkaline electrolyzers or proton-exchange membrane. [9][10][11][12][13][14][15] On the one hand, pairing the OER and HER catalysts together in the same electrolyte is of practical values to accomplish overall water splitting, which remains diffi cult to achieve owing to the incompatibility of the stability and activity for the same catalyst systems in the operating pH regions, thereby leading to inferior effi ciency; on the other hand, the different catalysts intended to separate HER and OER may need distinct synthetic strategies and instruments with lowthroughput preparation processes. [16][17][18][19][20] Therefore, it is still a grand challenge to exploit bifunctional electrocatalysts in terms of not only featuring high effi ciency toward both hydrogen and oxygen evolution reactions, but also simplifying the system and reducing the costs.Transition Co-based catalysts have been regarded as promising alternatives to noble metals to drive the half reactions, for instance, metal Co, [ 21 ] CoS, [ 22 ] and CoSe, [ 23 ] for HER and Co oxides/(oxy)hydroxides designed for OER. [ 24,25 ] Indeed, CoO xcarbon composites have been implemented to be bifunctional and effective electrocatalysts for overall water splitting in base, wherein the involvement of conductive carbonaceous hosts is to overcome the disadvantages of self-accumulation and insuffi cient electric conductivity as to oxides. [ 26,27 ] Nonetheless, the sophisticated preparation and instability of active phases in acid propose an obstacle to further optimize the technology and fi nd Water splitting for the production of hydrogen and oxygen is an appealing solution to advance many sustainable and renewable energy conversion and storage systems, while the key fact depends on the innovative exploration regarding the design of effi cient electrocatalysts. Reported herein is the growth of CoP mesoporous nanorod arrays on conductive Ni foam through an electrodeposition strategy. The resulting material of well-defi ned mesoporosity and a high specifi c surface area (148 m 2 g −1 ) can be directly employed as a bifunctional and fl exible working elect...

Graphitic carbon nitride (g-C3N4) has been deemed a promising heterogeneous metal-free catalyst for a wide range of applications, such as solar energy utilization toward water splitting, and its photocatalytic performance is reasonably adjustable through tailoring its texture and its electronic and optical properties. Here phosphorus-doped graphitic carbon nitride nanostructured flowers of in-plane mesopores are synthesized by a co-condensation method in the absence of any templates. The interesting structures, together with the phosphorus doping, can promote light trapping, mass transfer, and charge separation, enabling it to perform as a more impressive catalyst than its pristine carbon nitride counterpart for catalytic hydrogen evolution under visible light irradiation. The catalyst has low cost, is environmentally friendly, and represents a potential candidate in photoelectrochemistry.

The influence of defects on the photoactivity of ZnO has been revealed. The defects can be formed via ball-milling treatment, and part of the defects can be repaired via annealing treatment. The photocatalytic activity of the ZnO sharply decreased as the ballmilling speed and milling time increased. After the annealing treatment, the photocatalytic activity recovered partly but could not return to the activity of the pristine ZnO. The bulk defects such as oxygen vacancies (V O ), zinc vacancies (V Zn ) and a lot of nonradiative defects were formed after the milling treatment. The annealing treatment can only repair part of the bulk defects and nonradiative defects. Thus, only part of the photoactivity was recovered. The species trapping experiments showed that the introduction of the bulk defects did not change the photocatalytic mechanism. The main oxidative species for the pristine ZnO, the milled ZnO, and the annealed ZnO are photogenerated holes and hydroxyl radicals.

The nanocomposite photocatalysts of carbon-doped zinc oxide (ZnO) hybridized with graphitic carbon nitride (g-C 3 N 4 ) were prepared through simple one-step calcination of evaporation-dried mixture of dicyandiamide and zinc nitrate. Compared with pure ZnO and g-C 3 N 4 , the absorption of the prepared g-C 3 N 4 /ZnO nanocomposites shifted toward lower energy region, and the broader and stronger absorbance in the visible light region was observed, which was related to the content of g-C 3 N 4 in the nanocomposites. The photocatalytic activities of the resultant g-C 3 N 4 /ZnO nanocomposites for the degradation of methylene blue (MB) dye under visible light irradiation were enhanced remarkably and much higher than that of g-C 3 N 4 . The optimal content of g-C 3 N 4 in the prepared nanocomposites was found at a weight percent of 50.7%, which corresponded to the homogeneous hybridization between ZnO and g-C 3 N 4 . The improved photocatalytic performance of the g-C 3 N 4 /ZnO nanocomposites was ascribed to the elevation of the separation efficiency of photoinduced electron−hole pairs, resulting from the heterojunction established between the interfaces of g-C 3 N 4 and ZnO.

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Inorganic–organic metal phosphonate hybrid materials with great diversity in structure and properties exhibit application potential in various fields.

Metal-free ordered mesoporous carbons were demonstrated to be robust catalysts for direct dehydrogenation of propane to propylene, in the absence of any auxiliary steam, exhibiting high activity and selectivity, as well as long catalytic stability, in comparison with nanostructured carbons.