<span style="font-size:11.0pt;font-family: "Times New Roman";mso-fareast-font-family:"Times New Roman";mso-bidi-font-family: Mangal;mso-ansi-language:EN-GB;mso-fareast-language:EN-US;mso-bidi-language: HI" lang="EN-GB">Preparation of Pt/CeO₂-ZrO₂/carbon nanotubes hybrid catalysts for methanol electrooxidation</span>

868-872Pt/CeO2-ZrO2/multi-walled carbon nanotubes composites have been synthesized for the application of catalyst in direct methanol fuel cells. The introduction of CeO2-ZrO2, which has high surface area and oxygen storage capacity, can eliminate the toxic gases at low temperature. Electrocatalytic activity and stability of Pt/CeO2-ZrO2/MWCNT catalysts for methanol oxidation have been investigated with cyclic voltammetric and chronoamperometric techniques. Electrochemical measurements demonstrate that the Pt/CeO2-ZrO2/MWCNT catalysts exhibit superior electrocatalytic activities as compared with Pt/CeO2/MWCNT and Pt/MWCNT catalysts. The peak current density of Pt/CeO2-ZrO2/MWCNT catalysts for methanol electrooxidation is 3.9 times as high as that of Pt/MWCNT catalysts. The outstanding performance is likely to be due to the co-catalytic effect of CeO2-ZrO2 and the deposition manner of Pt nanoparticles

Understory fine roots are more ephemeral than those of trees in subtropical Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) stands

International audienceAbstract Key messageWe tested the life span of fine roots of Chinese fir trees and understory plants in two stands in subtropical China. Fine roots from understory plants were much more ephemeral than those from trees. The life span of fine roots of understory plants and Chinese fir was shorter in the younger than in the older stand, although most of the factors affecting fine-root life spans were similar between trees and understory plants. ContextUnderstory fine root can contribute significantly to total fine root biomass and belowground carbon. AimsThe contribution of understory vegetation to belowground carbon and nutrient cycling is often neglected in forest stands. Potential differences in fine-root life span between understory and trees remain poorly known. This study aimed to document fine-root life spans in trees and understory plants in two Chinese fir plantations with different ages. MethodsWe measured fine-root (≤2 mm in diameter) life span for trees and understory vegetation in 16- and 88-year-old Chinese fir plantations in southern China during 4 years with minirhizotron. Factors controlling fine-root life spans were identified with Cox proportional hazards regression. ResultsFine roots were more ephemeral in understory plants than in trees in the two plantations. Fine-root life spans for both trees and understory plants were longer in the older than in the younger plantation. Root diameter at appearance, rooting depth, and season of emergence had a significant effect on fine-root life span. ConclusionThese results highlight the importance of taking into account understory fine-root life span estimates when assessing the dynamics of fine-root recycling in Chinese fir forests

NiMoS₃ Nanorods as pH-Tolerant Electrocatalyst for Efficient Hydrogen Evolution

To meet the increasing demands for sustainable and clean hydrogen energy sources, development of pH-tolerant electrocatalysts with high-performance and low-cost toward hydrogen evolution reaction (HER) is an important but challenging task. MoS₂ is postulated as a promising candidate for HER in acidic solution, however, showing poor activity in alkaline media. Herein, to widen its application in various media, we first report the synthesis of NiMoS₃ nanorods using a hydrothermal method that starts from NiMoO₄ nanorods. The incorporation of Ni atoms in Mo–S could arouse the synergism of ternary Ni–Mo–S and create abundant defect sites, thus substantially improving the inherent catalytic activity and catalytic sites. More importantly, Ni endows Mo–S with excellent catalytic activity in alkaline solution. As a result, NiMoS₃ exhibits large cathodic current, low overpotetnial, and stable durability for HER in H₂SO₄ and especially in KOH. The overpotetnial at current density of 10 mA cm^–2 is as low as 126 mV in KOH, making it a promising candidate for HER electrocatalyst

Loading Pt Nanoparticles on Metal–Organic Frameworks for Improved Oxygen Evolution

An electrochemical oxygen evolution reaction (OER) is the crucial and limiting reaction in several renewable energy conversion systems, and metal–organic frameworks (MOFs) have triggered increasing research interests as potential catalysts toward OER. Deeper understanding of the OER activity over MOFs is extremely desired for the exploitation of robust MOFs-based electrocatalysts. Herein, Pt nanoparticles are loaded on Prussian blue analogues (Co₃[Fe­(CN)₆]₂ and Ni₃[Fe­(CN)₆]₂ nanocubes) to obtain improved catalytic activity. Co₃[Fe­(CN)₆]₂ and Ni₃[Fe­(CN)₆]₂ are rationally selected because of their containing of the fascinating transition metals of Co and Ni species. Using the hybrid catalyst as the modular system, we demonstrate the inspiring effect of Pt on the OER activity of MOFs. Detailed exploration conclusively demonstrates that Pt supplies combined advantages for the enhanced OER activity of MOFs, such as improving the intrinsic catalytic activity by tuning the valence state of transition metals (Co, Ni), increasing active sites, and enhancing charge transfer. Moreover, thorough electrochemical studies are also performed to declare the key role of Pt in the excellent catalytic activity and stability. We believe that introduction of trace amounts of Pt or other noble metals will be an effective solution to achieve a significant improvement in the OER activity of MOFs

FeNi Cubic Cage@N-Doped Carbon Coupled with N‑Doped Graphene toward Efficient Electrochemical Water Oxidation

Oxygen evolution reaction (OER) is of great significance in electrochemical water splitting on industrial scale, which suffers from the slow kinetics and large overpotential, thus setting the main obstacle for efficient water electrolysis. To pursue cost-effective OER electrocatalysts with high activity and durable stability, we here set a facile strategy to prepare N-doped graphene supported core–shell FeNi alloy@N-doped carbon nanocages (FeNi@NC-NG) by annealing graphene oxides supported Prussian blue analogues under H₂/Ar atmosphere. Based on the specific structural benefits, the present catalyst shows superior OER catalytic activity than precious metal catalyst of RuO₂ and Ir/C, with a low overpotential of 270 mV for 10 mA cm^–2, as well as high stability. The simple synthesis process and outstanding electrocatalytic performances show great potential of FeNi@NC-NG to replace the noble metal-based catalysts toward electrochemical water oxidation