Coupling interface engineering with electronic interaction toward high-efficiency H_(2) evolution in pH-universal electrolytes

Herein,the merits of heterojunction,CeO_(2),and W are employed to design and prepare the PtCoW@CeO_(2)heterojunction catalyst,which can accelerate water dissociation and improve the desorption of OHad,displaying efficient hydrogen evolution reaction(HER)performance in pH-universal conditions.Density functional theory calculation results reveal that the electronic structure of Pt is regulated by CeO_(2)and W,which tunes the Pt-Hadbond strength to boost HER intrinsic activity.Consequently,electrochemical results display that it has low potentials of-26,-25,and-23 mV at-10 mA cm^(-2)in alkaline,neutral,and acidic solutions,respectively,and it can stably cycle for 50,000 cycles.Thus,this work provides the guidance for developing high-performance Pt-based catalysts in pH-universal environments.

Novel ternary metals-based telluride electrocatalyst with synergistic effects of high valence non-3d metal and oxophilic Te for pH-universal hydrogen evolution reaction

Electrocatalyst designs based on oxophilic foreign atoms are considered a promising approach for developing efficient pH-universal hydrogen evolution reaction(HER)electrocatalysts by overcoming the sluggish alkaline HER kinetics.Here,we design ternary transition metals-based nickel telluride(Mo WNi Te)catalysts consisting of high valence non-3d Mo and W metals and oxophilic Te as a first demonstration of non-precious heterogeneous electrocatalysts following the bifunctional mechanism.The Mo WNi Te showed excellent HER catalytic performance with overpotentials of 72,125,and 182 mV to reach the current densities of 10,100,and 1000 mA cm^(-2),respectively,and the corresponding Tafel slope of 47,52,and 58 mV dec-1in alkaline media,which is much superior to commercial Pt/C.Additionally,the HER performance of Mo WNi Te is well maintained up to 3000 h at the current density of 100 mA cm^(-2).It is further demonstrated that the Mo WNi Te exhibits remarkable HER activities with an overpotential of 45 mV(31 mV)and Tafel slope of 60 mV dec-1(34 mV dec-1)at 10 mA cm^(-2)in neutral(acid)media.The superior HER performance of Mo WNi Te is attributed to the electronic structure modulation,inducing highly active low valence states by the incorporation of high valence non-3d transition metals.It is also attributed to the oxophilic effect of Te,accelerating water dissociation kinetics through a bifunctional catalytic mechanism in alkaline media.Density functional theory calculations further reveal that such synergistic effects lead to reduced free energy for an efficient water dissociation process,resulting in remarkable HER catalytic performances within universal pH environments.

Atomic Dispersion of Rh on Interconnected Mo_(2)C Nanosheet Network Intimately Embedded in 3D Ni_(x)MoO_(y) Nanorod Arrays for pH-Universal Hydrogen Evolution

Herein,a simple synthetic approach is employed for the atomic dispersion of Rh atoms(Rh SAs)over the surface of interconnected Mo_(2)C nanosheets intimately embedded in a three-dimensional Ni_(x)MoO_(y)nanorod arrays(Ni_(x)MoO_(y)NRs)framework;we found that the introduction of both isolated Rh SAs and Ni_(x)MoO_(y)NRs adjusts the electrocatalytic function of the host Mo_(2)C toward the direction of being an advanced and highly stable electrocatalyst for efficient hydrogen evolution at pH-universal conditions.As a result,the proposed catalyst outperforms most recently reported transition metal-based catalysts,and its performance even rivals that of commercial Pt/C,as demonstrated by its ultralow overpotentials of 31.7,109.7,and 95.4 mV at a current density of 10 mA cm^(-2),along with its small Tafel slopes of 42.4,51.2,and 46.8 mV dec^(-1)in acidic,neutral,and alkaline conditions,respectively.In addition,the catalyst shows remarkable long-term stability over all pH values with good maintenance of its catalytic activity and structural characteristics after continuous operation.

Highly active sites of NiVB nanoparticles dispersed onto graphene nanosheets towards efficient and pH-universal overall water splitting

Production of hydrogen(H2) and oxygen(O2) through electrocatalytic water splitting is one of the sustainable,green and pivotal ways to accomplish the ever-increasing demands for renewable energy sources,but remains a big challenge because of the uphill reaction during overall water splitting.Herein,we develop high-performance non-noble metal electrocatalysts for pH-universal water splitting,based on nickel/vanadium boride(NiVB) nanoparticles/reduced graphene oxide(rGO) hybrid(NiVB/rGO)through a facile chemical reduction approach under ambient condition.By virtue of more exposure to surface active sites,superior electron transfer capability and strong electronic coupling,the asprepared NiVB/rGO heterostructure needs pretty low overpotentials of 267 and 151 mV to deliver a current density of 10 mA cm^(-2) for oxygen evolution reaction(OER) and hydrogen evolution reaction(HER)respectively,with the corresponding Tafel slope of 44 and 88 mV dec^(-1) in 1.0 M KOH.Moreover,the NiVB/rGO electrocatalysts display a promising performance in a wide-pH conditions that require low overpotential of 310,353 and 489 mV to drive a current density of 10 mA cm^(-2) for OER under 0.5 M KOH,0.05 M H2SO4 and 1.0 M phosphate buffer solution(PBS) respectively,confirming the excellent electrocata lytic performance among state-of-the-art Ni-based electrocatalysts for overall water splitting.Therefore,the interfacial tuning based on incorporation of active heterostructure may pave a new route to develop bifunctional,cost-effective and efficient electrocatalyst systems for water splitting and H2 production.

Precise regulation of pyrrole-type single-atom Mn-N4 sites for superior pH-universal oxygen reduction

The study of atomically dispersed metal-nitrogen electrocatalysts is still limited in terms of understanding their catalytic mechanism because of the inability to precisely regulate the coordination number and type of N in combination with the metal elements.Inspired by the high catalytic activity and selectivity of natural enzymes,herein,we have designed and fabricated ultrathin carbon nanosheet-supported Mn single-atom catalysts(SACs)with a precise pyrrole-type Mn-N4(PT-MnN4)configuration using a bio-mimicking strategy.The PT-MnN4 SACs display outstanding oxygen reduction reaction(ORR)activity,with a half-wave potential(E_(1/2))of 0.88 V(vs.revisible hydrogen electrode[RHE])and extremely high stability in alkaline media.Moreover,superior ORR activities are also obtained,E_(1/2) of 0.73 V and 0.63 V in acid and neutral electrolytes,respectively,indicating the efficient pH-universal ORR performances.The assembled zinc-air battery using the PT-MnN4 SACs as air cathodes exhibits a high peak power density(175 mW cm^(−2))and long-term stability up to 150 h,implying its promising application in metal-air batteries.This study has paved the way toward the rational design and precise regulation of single-atom electrocatalysts.

Synergistic integration of self-supported 1T/2H-WS_(2) and nitrogendoped rGO on carbon cloth for pH-universal electrocatalytic hydrogen evolution

Hydrogen economy based on electrochemical water splitting exemplified one of the most promising means for overcoming the rapid consumption of fossil fuels and the serious deterioration of global climate.The development of earth-abundant,efficient,and durable electrocatalysts for hydrogen evolution reaction(HER)plays a vital role in the commercialization of water electrolysis.Regard,the self-supported electrode with unique nitrogen-doped reduced graphene oxide(N-rGO)nanoflakes and WS_(2) hierarchical nanoflower that were grown directly on carbon cloth(CC)substrate(WS_(2)/N-rGO/CC)was successfully synthesized using a facile dual-step hydrothermal approach.The as-synthesized 50%1T/2H-WS_(2)/N-rGO/CC(WGC),which possessed high metallic 1T phase of 57%not only efficiently exposed more active sites and accelerated mass/charge diffusion,but also endowed excellent structural lustiness,robust stability,and durability at a high current density.As a result,the 50%WGC exhibited lower overpotentials and Tafel slopes of 21.13 mV(29.55 mV∙dec^(-1))and 80.35 mV(137.02 mV∙dec^(-1))as compared to 20%Pt-C/CC,respectively for catalyzing acidic and alkaline hydrogen evolution reactions.Pivotally,the as-synthesized 50%WGC also depicted long-term stability for more than 8 h in the high-current-density regions(100 and 220 mA∙cm^(-2)).In brief,this work reveals a self-supported electrode as an extraordinary alternative to Pt-based catalysts for HER in a wide pH range,while paving a facile strategy to develop advanced electrocatalysts with abundant heterointerfaces for practical applications in energy-saving hydrogen production.

Vacancy engineering induced reaction kinetics enhancement of cobalt metaphosphate for pH-universal hydrogen evolution

Developing efficient pH-universal hydrogen evolution reaction(HER)catalysts is critical in the field of water electrolysis,however,which is severely hampered by the sluggish kinetics in alkaline media.Herein,a ruthenium(Ru)incorporation induced vacancy engineering strategy is firstly proposed to precisely construct oxygen vacancy(V_(O))-riched cobalt-ruthenium metaphosphate(CRPO)for high-efficiency pH-universal HER.The V_(O) modifies the electronic structure,improves the superficial hydrophilic and gas spillover capacity,it also reduces the coordination number of Ru atoms and regulates the coordination environment.Theoretical calculations indicate that Ru tends to adsorb H_(2)O and H^(*),whereas V_(O) tends to adsorb OH^(-),which greatly promotes the H_(2)O adsorption and the dissociation of HO-H bond.Ultimately,CRPO-2 exhibits remarkable HER performance,the mass activity is about 18.34,21.73,and 38.07 times higher than that of Pt/C in acidic,neutral,and alkaline media,respectively,at the same time maintain excellent stability.Our findings may pave a new avenue for the rational design of electrocatalysts toward pH-universal water electrolysis.

Mo-doped CoP nanoparticles anchored on porous Co-N-C framework as an efficient bifunctional electrocatalyst for pH-universal water splitting

Designing highly active and stable noble-metal-free electrocatalysts for water splitting over a wide pH range is critical yet remains significantly challenging.In this work,Mo-doped CoP nanoparticles(Mo-CoP)supported and enwrapped by porous single-atomic-Co doped carbon framework(Co-N-C)were designed and prepared by a simple one-pot pyrolysis method.The Mo-CoP/Co-N-C electrocatalyst exhibits superior performance with low overpotentials of only 45 mV for hydrogen evolution reaction(HER)and 201 mV for oxygen evolution reaction(OER)in 1 M KOH at 10 mA cm^(-2)current density.Such excellent catalytic activity can be ascribed to enhanced intrinsic activity,large surface area,and highly exposed active sites.Meanwhile,an extremely small overpotential of only 250 mV is required for a large current density of 500 mA cm^(-2)in HER,which exceeds the performance of benchmark 10%Pt/C.Besides,Mo-CoP/Co-N-C also exhibits superior HER performance in acidic and neutral mediums,with overpotentials of only 41 and 98 mV in 0.5 M H_(2)SO_(4),and 1 M PBS,respectively,thus achieving efficient water splitting at a wide pH range.The long-term stabilities are guaranteed with no significant decline of catalytic activities for more than 24 h in all electrolytes,which can be ascribed to the carbon layer encapsulation structure.Addition-ally,in overall water splitting,the electrocatalytic cell consisting of the as-synthesized Mo-CoP/Co-N-C only requires a cell voltage of 1.611 V at 100 mA cm^(-2)with excellent stability,exceeding that of the benchmark Pt/C||RuO(2) couple(1.645 V at 100 mA cm^(-2)).This work not only presents a highly efficient electrocatalyst for pH-universal water splitting but also provides a new perspective for the design and construction of transition metal catalysts with excellent stability.

Construction of pH-universal hydrogen evolution freeway in MoO_(3)-MoNi_(4)@Cu core-shell nanowires via synergetic electronic and geometric effect

Both the adsorption/dissociation of water molecules and hydrogen intermediate(H*)are the major limitations to hydrogen evolution reaction(HER).Herein,the modulation of electronic structure and geometric configuration are combined to design onedimensional electrocatalyst with outstanding HER activity in a wide pH range.The catalyst was composed of molybdenum trioxide doped molybdenum nickel alloy supported by copper nanowires(MoO_(3)-MoNi_(4)@Cu NWs).As revealed by the experimental characterizations and theoretical calculations,Cu NWs act as the electron donator to MoNi4,resulting in up shift of the d-band center in MoNi4,thus expediting H_(2)O adsorption and dissociation.Moreover,the introduction of amorphous MoO_(3) sets up a unique geometric configuration on MoNi4 for the accelerated H*transfer via hydrogen-bond and hydrogen spillover.This work provides a synergetic route for constructing HER freeway and promotes further investigations on more versatile electrocatalysis involving H_(2)O or H*.

Hierarchically structured flower-like Ru nanoparticles-cucurbit[6]uril/multiwalled carbon nanotubes as efficient pH-universal hydrogen evolution electrocatalyst

Developing efficient and stable electrocatalyst to hydrogen evolution reaction adaptable for electrolytes with different p H is a big challenge.In this work,a hierarchically structured ternary nanohybrid composed of flower-like Ru nanoparticles,rigid macrocyclic cucurbit[6]uril(CB[6])and carboxylated multiwalled carbon nanotubes(MWCNTs)was successfully prepared by chemical wet method.Benefited by the structural merits of flower-like Ru nanoparticles exposed abundant active sites supported by the MWCNTs holding superior mass transport and electrons transfer ability as well as the existence of CB[6],the obtained catalyst exhibited outstanding HER activities with overpotentials of 27,37 and 70 m V at-10 m A/cm^(2) in alkaline,acidic,and neutral electrolytes,respectively.Under the same electrocatalytic operation conditions,the HER performance is comparable or superior to commercial Pt/C catalyst(47,27and 49 m V).Besides,chronopotentiometric and accelerated stability test also revealed its extraordinary stability,which could be further employed for electrocatalytic procedure in a broad pH range.

Atomic Fe-Zn dual-metal sites for high-efficiency pH-universal oxygen reduction catalysis

An effective electrocatalyst being highly active in all pH range for oxygen reduction reaction(ORR)is crucial for energy conversion and storage devices.However,most of the high-efficiency ORR catalysis was reported in alkaline conditions.Herein,we demonstrated the preparation of atomically dispersed Fe-Zn pairs anchored on porous N-doped carbon frameworks(Fe-Zn-SA/NC),which works efficiently as ORR catalyst in the whole pH range.It achieves high half-wave potentials of 0.78,0.85 and 0.72 V in 0.1 M HClO4,0.1 M KOH and 0.1 M phosphate buffer saline(PBS)solutions,respectively,as well as respectable stability.The performances are even comparable to Pt/C.Furthermore,when assembled into a Zn-air battery,the high power density of 167.2 mWcm−2 and 120 h durability reveal the feasibility of Fe-Zn-SA/NC in real energy-related devices.Theoretical calculations demonstrate that the superior catalytic activity of Fe-Zn-SA/NC can be contributed to the lower energy barriers of ORR at the Fe-Zn-N6 centers.This work demonstrates the potential of Fe-Zn pairs as alternatives to the Pt catalysts for efficient catalytic ORR and provides new insights of dual-atom catalysts for other energy conversion related catalytic reactions.

Boosting pH-Universal Hydrogen Evolution of Molybdenum Disulfide Particles by Interfacial Engineering

The design of high-efficiency non-noble and earth-abundant electrocatalysts for hydrogen evolution reaction(HER)is highly paramount for water splitting and renewable energy systems.Molybdenum disulfide(MoS_(2))with abundant edge sites can be utilized as a promising alternative,but its catalytic activity is greatly related to the pH values,especially in an alkaline environment due to the extremely high energy barriers for water adsorption and dissociation steps.Here we report an exceptionally efficient and stable electrocatalyst to improve the sluggish HER process of layered MoS_(2)particles in different pH electrolytes,especially in base.The electrocatalyst is constructed by in situ growing selenium-doped MoS_(2)(Se-MoS_(2))nanoparticles on three-dimensional cobalt nickel diselenide(mCo_(0.2)Ni_(0.8)Se_(2))nanostructured arrays.Due to the large number of active edge sites of Se-MoS_(2)particles exposed at the surface,robust electrical conductivity and large surface area of mCo_(0.2)Ni_(0.8)Se_(2)support,and strong interfacial interactions between Se-MoS_(2)and mCo_(0.2)Ni_(0.8)Se_(2),this hybrid catalyst shows very outstanding catalytic HER properties featured by low overpotentials of 30 and 122 mV at 10 and 100 mA/cm^(2)with good operational stability in base,respectively,which outperforms most of inexpensive catalysts consisting of layered MoS_(2),transition metal selenides and sulfides,and it performs as well as noble Pt catalysts.Meanwhile,this electrocatalyst is also very active in neutral and acidic electrolytes,requiring low overpotentials of 93 and 94 mV at 10 mA/cm^(2),respectively,demonstrating its superb pH universality as a HER electrocatalyst with excellent catalytic durability.This study provides a straightforward strategy to construct an efficient non-noble electrocatalyst for driving the HER kinetics in different electrolytes.

Electron-transfer enhanced MoO2-Ni heterostructures as a highly efficient pH-universal catalyst for hydrogen evolution

Hydrogen is one of the most promising energy carriers to replace fossil fuels and electrolyzing water to produce hydrogen is a very effective method.However,designing highly active and stable non-precious metal hydrogen evolution electrocatalysts that can be used in universal pH is a huge challenge.Here,we have reported a simple strategy to develop a highly active and durable non-precious MoO2-Ni electrocatalyst for hydrogen evolution reaction(HER)in a wide pH range.The MoO2-Ni catalyst exhibits a superior electrocatalytic performance with low overpotentials of 46,69,and 84 mV to reach-10 mA cm-2 in 1.0 M KOH,0.5 M H2SO4,and 1.0 M PBS electrolytes,respectively.At the same time,the catalyst also shows outstanding stability over a wide pH range.It is particularly noted that the catalytic performance of MoO2-Ni in alkaline solution is comparable to the highest performing catalysts reported.The outstanding HER performance is mainly attributed to the collective effect of the rational morphological design,electronic structure engineering,and strong interfacial coupling between MoO2 and Ni in heterojunctions.This work provides a viable method for the synthesis of inexpensive and efficient HER electrocatalysts for the use in wide pH ranges.

Tunable Ru-Ru2P heterostructures with charge redistribution for efficient pH-universal hydrogen evolution

Designing synergistic heterogeneous catalytic interfaces is the key to developing highly compatible pH-universal electrocatalysts for complex chemical environments.Our theoretical calculation results demonstrate that the Ru-Ru2P heterointerface can not only promote the redistribution of charges,but also reduce the d-band center,and then enhances the adsorption capacity of the key intermediate.However,in situ and facile synthesis of Ru-Ru2P heterostructures is severely limited by thermodynamic obstacles.Herein,we propose a molten salt-assisted catalytic synthesis scheme,and successfully build a series of homologous metallic Ru-Ru2P heterostructure catalysts with different molar ratios of Ru to P under atmospheric pressure and low-temperature(400C).The resultant Ru-Ru2P with rich heterostructures show the Pt-like HER performance in different pH media.Particularly,it is prominent under alkaline conditions(18 mV@10 mA cm^(2)),which outperforms the Pt catalyst(37 mV@10 mA cm^(2)).Furthermore,Ru-Ru2P heterostructures also show certain potential in the electrolysis of seawater to produce hydrogen.This work represents a significant supplement of high-efficiency pH-universal HER catalysts,and provides a new light on interface engineering in energy technology fields and beyond.

Interfacial engineering of 3D hollow CoSe_(2)@ultrathin MoSe_(2)core@shell heterostructure for efficient pH-universal hydrogen evolution reaction

Rational design and construction of low-cost and highly efficient electrocatalysts for hydrogen evolution reaction(HER)is meaningful but challenging.Herein,a robust three dimensional(3D)hollow CoSe_(2)@ultrathin MoSe_(2)core@shell heterostructure(CoSe_(2)@MoSe_(2))is proposed as an efficient HER electrocatalyst through interfacial engineering.Benefitting from the abundant heterogeneous interfaces on CoSe_(2)@MoSe_(2),the exposed edge active sites are maximized and the charge transfer at the hetero-interfaces is accelerated,thus facilitating the HER kinetics.It exhibits remarkable performance in pH-universal conditions.Notably,it only needs an overpotential(η10)of 108 mV to reach a current density of 10 mA·cm^(-2)in 1.0 M KOH,outperforming most of the reported transition metal selenides electrocatalysts.Density functional theory(DFT)calculations unveil that the heterointerfaces synergistically optimize the Gibbs free energies of H2O and H^(*)during alkaline HER,accelerating the reaction kinetics.The present work may provide new construction guidance for rational design of high-efficient electrocatalysts.

Metal-organic framework derived NiCoP hollow polyhedrons electrocatalyst for pH-universal hydrogen evolution reaction

Hollow nanostructures have attracted increasing research interest in hydrogen evolution reaction owing to their unique structural features.Herein,Ni-Co mixed metal phosphide hollow and porous polyhedrons was successfully composited(expressed as NiCoP).Benefiting from the synergistic effects of ZIF-67 by doping Ni elements and the well-defined hollow and porous structure,the as-synthesized NiCoP hollow and porous polyhedrons exhibit better electrochemical properties and mechanical stability for hydrogen evolution reaction over a pH-universal range,with a small Tafel slopes of 72,101,176 mV/dec,and a low overpotential of 82,102,261 mV at a current density of 10 mA/cm^(2) in 0.5 mol/L H_(2)SO_(4),1 mol/L KOH and1 mol/L phosphate buffer solution(PBS).This general strategy can also be applied to fabricate other hollow cobalt-based phosphides and MOFs-derived materials for HER.

Tuning the electronic structure of NiCoP arrays through V doping for pH-universal hydrogen evolution reaction electrocatalyst

The exploration of cost-effective,high-performance,and stable electrocatalysts for the hydrogen evolution reaction(HER)over wide pH range(0–14)is of paramount importance for future renewable energy conversion technologies.Regulation of electronic structure through doping vanadium atoms is a feasible construction strategy to enhance catalytic activities,electron transfer capability,and stability of the HER electrode.Herein,V-doped NiCoP nanosheets on carbon fiber paper(CFP)(denoted as Vx-NiCoP/CFP)were constructed by doping V modulation on NiCoP nanosheets on CFP and used for pH-universal HER.Benefiting from the abundant catalytic sites and optimized hydrogen binding thermodynamics,the resultant V15-NiCoP/CFP demonstrates a significantly improved HER catalytic activity,requiring overpotentials of 46.5,52.4,and 85.3 mV to reach a current density of 10 mA·cm^(−2)in 1 mol·L^(−1) KOH,0.5 mol·L^(−1) H_(2)SO_(4),and 1 mol·L^(−1) phosphate buffer solution(PBS)electrolytes,respectively.This proposed cation-doping strategy provides a new inspiration to rationally enhance or design new-type nonprecious metal-based,highly efficient,and pH-universal electrocatalysts for various energy conversion systems.

Pt nanodendrites with (111) crystalline facet as an efficient, stable and pH-universal catalyst for electrochemical hydrogen production

High-performance nanomaterial catalysts for hydrogen evolution reaction via electrochemical water splitting are significant to the development of hydrogen energy.In this work,we report a robust and highly active catalyst fabricated through direct electrochemical deposition of Pt nanodendrites at the surface of activated carbon(Pt NDs).Owing to the large elect roc he mically active area and the exposed(111) facet of Pt,Pt NDs exhibits outstanding activity towards hydrogen evolution reaction with a low requiring overpotential of 0.027 V at 10 mA/cm2 and Tafel slope of ≈22 mV/dec in acidic media.In addition,the hydrogen yield of Pt NDs is 30%-45% larger than that of commercial Pt/C at the same Pt loadings.Moreover,Pt NDs exhibits excellent lo ng-term durability whose hydrogen production efficiency remains unchanged after six-hour hydrogen production,while the efficiency of commercial Pt/C catalyst decayed 9% under the same circumstance.Considering the superiority of catalytic activity and stability,this Pt NDs present great potentiality towards practical hydrogen production application.

Highly efficient pH-universal hydrogen evolution reaction catalyzed by rapidly reconstructed bimetallic cobalt-molybdenum alloy cuboids arrays

Given the inherent potential of seawater,industrial wastewater,and residential water as inherent feedstocks for hydrogen production through water electrolysis,there is a critical demand for the exploration of robust and stable hydrogen-evolving catalysts that can operate effectively across a diverse range of pH conditions.However,the pursuit of hydrogen-evolving electrocatalysts that demonstrate both good stability and high efficiency over a wide pH range remains a formidable challenge.Here we report the rational design and synthesis of an outstanding nanoporous hybrid electrocatalyst consisting of intermetallic cobalt-molybdenum alloy particles anchoring on MoO2 cuboid arrays,which demands very low overpotentials of 72,123 and 134 mV to deliver a current density of−100 mA·cm^(−2)for hydrogen evolution reaction under alkaline,neutral and acidic conditions,respectively.These catalytic activities are superior to most non-precious-metal-based catalysts documented in the literatures,and are even comparable to noble metal catalysts.In particular,this alloy electrocatalyst exhibits excellent stability at 50 or 300 mA·cm^(−2)without obvious activity degradation,which is further supported by the undetectable changes in the surface chemical valence states on the basis of in-situ X-ray photoelectron spectroscopic studies.This study provides an innovative strategy for the design and synthesis of effective non-noble intermetallic catalysts for pH-universal hydrogen evolution over a wide pH range.

A new Keggin-type polyoxometallate-based bifunctional catalyst for trace detection and pH-universal photodegradation of phenol

The widespread application of phenolic substances in the field of food,medicine and industry,is harmful to the environment and human health.Therefore,it is very important to develop a con-venient and effective method to detect and degrade phenolic compounds.Herein,we report a new keggin-type polyoxometallate-based metal-organic complex self-assembled under solvothermal condition,{[Cu(dap)(3-PA)]4(SiW_(12)O_(40))(H_(2)O)_(2)}·2H_(2)O(1,dap=1,2-diaminopropane,3-HPA=3-pyridineacrylic acid).1 shows an interesting 1D ladder-like structure.As a bifunctional catalyst,1 can be employed as a colori-metric sensor toward phenol with the relatively low detection limit(LOD)of 0.36μmol/L(S/N=3)in the wide range(0.001-0.1 mmol/L).The title colorimetric sensor is applied to determine phenol in various water environment with good recoveries ranging from 95%-105%.In addition,1 also exhibits excellent photocatalytic degradation toward phenol under visible light with the highest removal efficiency at 96%for 100 min and wide pH universality.The selectivity,stability and reliability of the detection of 1 towards phenol,as well as the detection for 4-chlorophenol,o-cresol,4-nitrophenol and phloroglucinol were stud-ied.Furthermore,the photocatalytic reaction kinetics and the mechanisms of photodegradation of phenol were also investigated in detail.