In-situ surface self-reconstruction in ternary transition metal dichalcogenide nanorod arrays enables efficient electrocatalytic oxygen evolution

Water splitting has received more and more attention because of its huge potential to generate clean and renewable energy.The highly active and durable oxygen evolution reaction(OER)catalysts play a decisive factor in achieving efficient water splitting.The identification of authentic active origin under the service conditions can prompt a more reasonable design of catalysts together with well-confined micro-/nano-structures to boost the efficiency of water splitting.Herein,Fe,Co,and Ni ternary transition metal dichalcogenide(FCND)nanorod arrays on Ni foam are purposely designed as an active and stable low-cost OER pre-catalyst for the electrolysis of water in alkaline media.The optimized FCND catalyst demonstrated a lower overpotential than the binary and unary counterparts,and a 27-fold rise in kinetic current density at the overpotential of 300 m V compared to the nickel dichalcogenide counterpart.Raman spectra and other structural characterizations at different potentials reveal that the in-situ surface self-reconstruction from FCND to ternary transition metal oxyhydroxides(FCNOH)on catalyst surfaces initiated at about 1.5 V,which is identified as the origin of OER activity.The surface selfreconstruction towards FCNOH also enables excellent stability,without fading upon the test for 50 h.

Structural self-reconstruction strategy empowering Ni-rich layered cathodes with low-strain for superior cyclabilities

The key to hindering the commercial application of Ni-rich layered cathode is its severe structural and interface degradation during the undesired phase transition(hexagonal to hexagonal(H2→H3)),degenerating from the build-up of mechanical strain and undesired parasitic reactions.Herein,a perovskite Li_(0.35)La_(0.55)TiO_(3)(LLTO)layer is built onto Ni-rich cathodes crystal to induce layered@spinel@perovskite heterostructure to solve the root cause of capacity fade.Intensive exploration based on structure characterizations,in situ X-ray diffraction techniques,and first-principles calculations demonstrate that such a unique heterostructure not only can improve the ability of the host structure to withstand the mechanical strain but also provides fast diffusion channels for lithium ions as well as provides a protective barrier against electrolyte corrosion.Impressively,the LLTO modified LiNi_(0.9)Co_(0.05)Mn_(0.05)O_(2)cathode manifests an unexpected cyclability with an extremely high-capacity retention of≈94.6%after 100 cycles,which is superior to the pristine LiNi_(0.9)Co_(0.05)Mn_(0.05)O_(2)(79.8%).Furthermore,this modified electrode also shows significantly enhanced cycling stability even withstanding a high cut-off voltage of 4.6 V.This surface self-reconstruction strategy provides deep insight into the structure/interface engineering to synergistically stabilize structure stability and regulate the physicochemical properties of Ni-rich cathodes,which will also unlock a new perspective of surface interface engineering for layered cathode materials.

The photo-decomposition and self-restructuring dynamic equilibrium mechanism of Cu_(2)(OH)_(2)CO_(3)for stable photocatalytic CO_(2)reduction

Developing suitable photocatalysts and understanding their intrinsic catalytic mechanism remain key challenges in the pursuit of highly active,good selective,and long-term stable photocatalytic CO_(2)reduction(PCO_(2)R)systems.Herein,monoclinic Cu_(2)(OH)_(2)CO_(3)is firstly proven to be a new class of photocatalyst,which has excellent catalytic stability and selectivity for PCO_(2)R in the absence of any sacrificial agent and cocatalysts.Based on a Cu_(2)(OH)_(2)^(13)CO_(3)photocatalyst and 13CO_(2)two-sided^(13)C isotopic tracer strategy,and combined with in situ diffused reflectance infrared Fourier transform spectroscopy(DRIFTS)analysis and density functional theory(DFT)calculations,two main CO_(2)transformation routes,and the photo-decomposition and self-restructuring dynamic equilibrium mechanism of Cu_(2)(OH)_(2)CO_(3)are definitely revealed.The PCO_(2)R activity of Cu_(2)(OH)_(2)CO_(3)is comparable to some of state-of-the-art novel photocatalysts.Significantly,the PCO_(2)R properties can be further greatly enhanced by simply combining Cu_(2)(OH)_(2)CO_(3)with typical TiO_(2)to construct composites photocatalyst.The highest CO_(2)and CH_(4)production rates by 7.5 wt%Cu_(2)(OH)_(2)CO_(3)-TiO_(2)reach 16.4μmol g^(-1)h^(-1)and 116.0μmol g^(-1)h^(-1),respectively,which are even higher than that of some of PCO_(2)R systems containing sacrificial agents or precious metals modified photocatalysts.This work provides a better understanding for the PCO_(2)R mechanism at the atomic levels,and also indicates that basic carbonate photocatalysts have broad application potential in the future.

Unlocking the electrocatalytic activity of natural chalcopyrite using mechanochemistry

Manipulating the structure self-reconstruction of transition metal sulfide-based(pre)catalysts during the oxygen evolution reaction(OER) process is of great interest for developing cost-effective OER catalysts,which remains a central challenge. Here we realize a deep structure self-reconstruction of natural chalcopyrite to unlock its OER performance via mechanochemical activation. Compared with the manually milled counterpart(CuFeS_(2)-HM), the mechanically milled catalyst(CuFeS_(2)-BM) with a reduced crystallinity exhibits a 7.11 times higher OER activity at 1.53 V vs. RHE. In addition, the CuFeS_(2)-BM requires a low overpotential of 243 mV for generating 10 mA cm^(-2) and exhibits good stability over 24 h. Further investigations suggest that the excellent OER performance of CuFeS_(2)-BM mainly originates from the decreased crystallinity induced the in situ deep structure self-reconstruction of the originally sulfides into the electroactive and stable metal(oxy)hydroxide phase(e.g., a-Fe OOH) via S etching under OER conditions. This study demonstrates that regulating the crystallinity of catalysts is a promising design strategy for developing highly efficient OER catalysts via managing the structure self-reconstruction process, which can be further extended to the design of efficient catalysts for other advanced energy conversion devices. In addition, this study unveils the great potentials of engineering abundant natural minerals as cost-effective catalysts for diverse applications.

Non-noble metal-based amorphous high-entropy oxides as efficient and reliable electrocatalysts for oxygen evolution reaction

Exploring high-performance and cost-effective electrocatalysts that are applicable in oxygen evolution reaction(OER)is crucial for water splitting and energy storage.In this work,a facile and scalable chemical reduction strategy is developed to synthesize FeCoNiPB non-noble metal-based amorphous high-entropy oxides for the OER in alkaline media.The FeCoNiPB oxides exhibit overpotentials of 235 and 306 mV at current densities of 10 and 100 mA/cm^(2),respectively,as well as a small Tafel slope of 53 mV/dec in 1.0 M KOH solution,outperforming the performance of FeCoPB,FeNiPB,and CoNiPB oxides and the commercial RuO_(2),while maintaining excellent stability with negligible overpotential amplification over 40 h.The superior OER electrocatalytic efficiency and stability of the FeCoNiPB catalyst is primarily attributed to its unique amorphous high-entropy nanostructure,synergistic effect of the multiple components,and in situ-formed amorphous sheets with a thin(FeCoNi)OOH crystalline layer on the edge during long-term OER.This work provides new insights to design and prepare low-cost,highly efficient,and durable OER electrocatalysts.

FeNiS_(2)/reduced graphene oxide electrocatalysis with reconstruction to generate FeNi oxo/hydroxide as a highly-efficient water oxidation electrocatalyst

It is critical to developing electrocatalysts with highly active and cost-effective for oxygen evolution to resolve environmental pollution and energy issues,in which FeNi-based nanomaterials hold a great promise.Herein,(Fe_(0.33 )Ni_(0.67))S_(2) and(Fe_(0.33 )Ni_(0.67))S_(2)/reduced graphene oxide(rGO)-x%(x=10,20) composites,which exhibited highly efficient oxygen evolution reaction(OER)electrocatalytic activity under alkaline conditions,were synthesized via a hydrothermal approach and following thermal treatment with sulfur powders.Benefiting from the integrated structure of(Fe_(0.33 )Ni_(0.67))S_(2)and support of conductive graphene backbones,(Fe_(0.33 )Ni_(0.67))S_(2)/rGO-20%electrocatalyst showed the best OER activity with an overpotential of 172 mV at 10 mA·cm^(-2)and Tafel slopes of 45 mV·decade^(-1).The composition,phase,and surface structure of the catalyst were characterized before and after OER reaction.The results indicated that crystal phase of the catalyst was reconstructed to the amorphous crystalline features after OER,with oxidation of iron-nickel sulfide and appearance of Ni-Fe oxo/hydroxide species,which may play a crucial role in the high OER performance as the catalytic-active.Moreover,in a two-electrode system towards overall water splitting with(Fe_(0.33 )Ni_(0.67))S_(2)/rGO-20%/NF and Pt/C/NF as the anode and cathode,respectively,the catalysts exhibited excellent catalytic performance with the voltage of only 1.42 V at 10 mA·cm^(-2).

Wengongtuan and the Rural Literary Popularization Movement in Yan＇an

This paper takes the folk song collection movement in Yan＇an as an example to examine the role of the wengongtuan （The League of Literary and Artistic Workers） in organizing the rural literary popularization movement in the 1940s. Dispatched by the Communist Party of China （CPC）, wengongtuan members took on the task of mobilizing peasants into cultural production, and realized a self-reconstruction in the process of integrating themselves into the lives of revolutionary peasants. The idea of the wengongtuan derived from the CPC＇s theory of the mass line--＂from the masses and to the masses＂--which laid the foundation of New Democratic culture in the 1940s.