Co-catalyst-free large ZnO single crystal for high-efficiency piezocatalytic hydrogen evolution from pure water

Piezocatalytic materials have been widely used for catalytic hydrogen evolution and purification of organic contaminants.However,most studies focus on nano-size and/or polycrystalline catalysts,suffering from aggregation and neutralization of internal piezoelectric field caused by polydomains.Here we report a single crystal ZnO of large size and few bulk defects crafted by a hydrothermal method for piezocatalytic hydrogen generation from pure water.It is noteworthy that single-side surface areas of both original as-prepared ZnO and Ga-doped ZnO bulk crystals are larger than 30 cm^(2).The high quality of ZnO and Ga-doped ZnO bulks are further uncovered by high-resolution transmission electron microscope(HRTEM),photoluminescence(PL)and X-ray diffraction(XRD).Remarkably,an outstanding hydrogen production rate of co-catalyst-free Ga-doped ZnO bulk crystal(i.e.,a maximum rate of 5915μmol h^(-1) m^(-2))is observed in pure water triggered by ultrasound in dark,which is over 100 times higher than that of its powder counterpart(i.e.,52.54μmol h^(-1) m^(-2)).The piezocatalytic performance of ZnO bulk crystal is systematically studied in terms of varied exposed crystal facet,thickness and conductivity.Different piezocatalytic performances are attributed to magnitude and distribution of piezoelectric potential,revealed by the finite element method(FEM)simulation.The density functional theory(DFT)calculations are employed to investigate the piezocatalytic hydrogen evolution process,indicating a strong H_(2)O adsorption and a low energy barrier for both H_(2)O dissociation and H2 generation on the stressed Znterminated(0001)ZnO surface.

Polar solvent induced in-situ self-assembly and oxygen vacancies on Bi_(2)MoO_(6)for enhanced photocatalytic degradation of tetracycline

It has been proved to be an effective route to efficiently ameliorate photocatalytic performance of catalysts via designing three-dimensional(3D)hierarchical nanostructures and constructing oxygen vacancies(VOs).However,controlling the self-assembly of organization into 3D hierarchical nanostructures while introducing VOs in photocatalysts remains a challenge.Herein,we reported an ethylene glycol(EG)mediated approach to craft 3D hydrangea-structure Bi_(2)MoO_(6)with VOs for efficient photocatalytic degradation of tetracycline.Through manipulating the EG concentration during the fabrication process,the influence of EG concentration on the Bi_(2)MoO_(6)structure was systematically investigated.EG could promote the self-assembly of Bi_(2)MoO_(6)nanosheets to form a 3D hierarchical structure.Compared with 2D nanoplates,3D hierarchical architecture enhanced the surface area and the amount of active sites of Bi_(2)MoO_(6).In addition,the reduction effect of EG on metallic oxide enabled the generation of VOs in Bi_(2)MoO_(6).The VOs adjusted the electronic structure of Bi_(2)MoO_(6),which not only enhanced the light harvesting,but also facilitated the simultaneous utilization of photo-induced electrons and holes to form reactive oxygen species(·O2−and·OH)for the efficient tetracycline decomposition.3D Bi_(2)MoO_(6)hydrangea with VOs achieved a 79.4%removal efficiency of tetracycline after 75 min.This work provides a simple yet robust EG-mediated strategy,which not only promotes the self-assembly of nano-catalysts into 3D hierarchical architectures,but also crafts tunable VOs for highly efficient photocatalysis.

A multi-terminal ion-controlled transistor with multifunctionality and wide temporal dynamics for reservoir computing

Reservoir computing(RC)is an energy-efficient computational framework with low training cost and high efficiency in processing spatiotemporal information.The state-of-the-art fully memristor-based hardware RC system suffers from bottlenecks in the computation efficiencies and accuracy due to the limited temporal tunability in the volatile memristor for the reservoir layer and the nonlinearity in the nonvolatile memristor for the readout layer.Additionally,integrating different types of memristors brings fabrication and integration complexities.To overcome the challenges,a multifunctional multi-terminal electrolyte-gated transistor(MTEGT)that combines both electrostatic and electrochemical doping mechanisms is proposed in this work,integrating both widely tunable volatile dynamics with high temporal tunable range of 10^(2) and nonvolatile memory properties with high long-term potentiation/long-term depression(LTP/LTD)linearity into a single device.An ion-controlled physical RC system fully implemented with only one type of MTEGT is constructed for image recognition using the volatile dynamics for the reservoir and nonvolatility for the readout layer.Moreover,an ultralow normalized mean square error of 0.002 is achieved in a time series prediction task.It is believed that the MTEGT would underlie next-generation neuromorphic computing systems with low hardware costs and high computational performance.

Te-mediated electro-driven oxygen evolution reaction

In the 21^(st)century,the rapid development of human society has made people’s demand for green energy more and more urgent.The high-energy-density hydrogen energy obtained by fully splitting water is not only environmentally friendly,but also is expected to solve the problems caused by the intermittent nature of new energy.However,the slow kinetics and large overpotential of the oxygen evolution reaction(OER)limit its application.The introduction of Te element is expected to bring new breakthroughs.With the least electronegativity among the chalcogens,the Te element has many special properties,such as multivalent states,strong covalentity,and high electrical conductivity,which make it a promising candidate in electrocatalytic OER.In this review,we introduce the peculiarities of Te element,summarize Te doping and the extraordinary performance of its compounds in OER,with emphasis on the scientific mechanism behind Te element promoting the OER kinetic process.Finally,challenges and development prospects of the applications of Te element in OER are presented.

Robust route to H_(2)O_(2)and H_(2)via intermediate water splitting enabled by capitalizing on minimum vanadium-doped piezocatalysts

H_(2)O_(2)is an environmentally friendly chemical for a wide range of water treatments.The industrial production of H_(2)O_(2)is an anthraquinone oxidation process,which,however,consumes extensive energy and produces pollution.Here we report a green and sustainable piezocatalytic intermediate water splitting process to simultaneously obtain H_(2)O_(2)and H_(2)using single crystal vanadium(V)-doped NaNbO_(3)(V-NaNbO_(3))nanocubes as catalysts.The introduction of V improves the specific surface area and active sites of NaNbO_(3).Notably,V-NaNbO_(3)piezocatalysts of 10 mg exhibit 3.1-fold higher piezocatalytic efficiency than the same catalysts of 50 mg,as more piezocatalysts lead to higher probability of aggregation.The aggregation causes reducing active sites and decreased built-in electric field due to the neutralization between different nano-catalysts.Remarkably,piezocatalytic H_(2)O_(2)and H_(2)production rates of V-NaNbO_(3)(10 mol%)nanocubes(102.6 and 346.2μmol·g^(−1)·h^(−1),respectively)are increased by 2.2 and 4.6 times compared to the as-prepared pristine NaNbO_(3)counterparts,respectively.This improved catalytic efficiency is attributed to the promoted piezo-response and more active sites of NaNbO_(3)catalysts after V doping,as uncovered by piezoresponse force microscopy(PFM)and density functional theory(DFT)simulation.More importantly,our DFT results illustrate that inducing V could reduce the dynamic barrier of water dissociation over NaNbO_(3),thus enhancing the yield of H_(2)O_(2)and H_(2).This facile yet robust piezocatalytic route using minimal amounts of catalysts to obtain H_(2)O_(2)and H_(2)may stand out as a promising candidate for environmental applications and water splitting.

Upcycling electroplating sludge into bioengineering-enabled highly stable dual-site Fe-Ni_(2)P@C electrocatalysts for efficient oxygen evolution

The advancement of bimetallic catalysts holds significant promise for the innovation of oxygen evolution reaction(OER)catalysts.Drawing from adsorbate evolution mechanism(AEM)and lattice oxygen oxidation mechanism(LOM),the incorporation of dual active sites has the potential to foster novel OER pathways,such as the coupled oxygen evolution mechanism(COM),which can surpass the limitations of OER and elevate catalytic performance.In this study,uniformly distributed Fe/Ni dual-site Fe-Ni_(2)P@C electrocatalysts are crafted by upcycling metals in electroplating sludge via an eco-friendly and sustainable microbial engineering technique.Our findings indicate that a substantial number of defects emerge at the Ni2P crystal during the OER process,laying the groundwork for lattice oxygen involvement.Moreover,the displacement of Ni/Fe in the crystal lattice intensifies the asymmetry of the electronic structure at the metal active sites,facilitating the deprotonation process.This research introduces an innovative paradigm for the synthesis of effective and robust transition metal-based OER catalysts,with implications for sustainable energy generation technologies.