Pyridinic-N doping carbon layers coupled with tensile strain of FeNi alloy for activating water and urea oxidation

Exploitation of oxygen evolution reaction(OER)and urea oxidation reaction(UOR)catalysts with high activity and stability at large current density is a major challenge for energy-saving H_(2) production in water electrolysis.Herein,we use the pyridinic-N doping carbon layers coupled with tensile strain of FeNi alloy activated by NiFe_(2)O_(4)(FeNi/NiFe_(2)O_(4)@NC)for efficiently increasing the performance of water and urea oxidation.Due to the tensile strain effect on FeNi/NiFe_(2)O_(4)@NC,it provides a favorable modulation on the electronic properties of the active center,thus enabling amazing OER(η_(100)=196 mV)and UOR(E_(10)=1.32 V)intrinsic activity.Besides,the carbon-coated layers can be used as armor to prevent FeNi alloy from being corroded by the electrolyte for enhancing the OER/UOR stability at large current density,showing high industrial practicability.This work thus provides a simple way to prepare high-efficiency catalyst for activating water and urea oxidation.

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.

Tailoring the selective adsorption sites of NiMoO by Ni particles for biomass upgrading assisted hydrogen production

5-Hydroxymethylfurfural electrooxidation reaction(HMFOR)is a promising route to produce valueadded chemicals from biomass.Since it involves HMF adsorption and C-H/O-H cleavage,understanding the adsorption behavior and catalytic process of organic molecules on catalysts is important.Herein,the selective adsorption sites of NiMoO are tuned by Ni particles for HMFOR-assisted H2production.Experimental and theoretical calculation results indicate that the synergistic interaction between Ni and NiMoO optimizes the adsorption/desorption of HMF/intermediates/2,5-furandicarboxylic acid(FDCA)and promotes the C-H/O-H bond cleavage,thereby improving the HMFOR kinetics(kNiMoO-Ni/kNiMoO=1.97)and FDCA selectivity(99.3%).When coupled as a two-electrode system,it can drive efficient HMF conversion(FDCA yield:98.5%)and H2production(Faradaic efficiency:99.1%)at 1.45 V.This work thus offers a strategy to tune the adsorption sites of catalyst for efficient HMFOR-assisted H2production.

Strong electronic coupling of CoNi and N-doped-carbon for efficient urea-assisted H2 production at a large current density

Exploiting efficient urea oxidation reaction(UOR)and hydrogen evolution reaction(HER)catalysts are significant for energy-saving H2 production through urea-assisted water electrolysis,but it is still challenging.Herein,carbon-encapsulated CoNi coupled with CoNiMoO(CoNi@CN-CoNiMoO)is prepared by solvothermal method and calcination to enhance the activity/stability of urea-assisted water electrolysis at large current density.It exhibits good activity for UOR(E10/1,000=1.29/1.40 V)and HER(E-10/-1000=-45/-245 mV)in 1.0 M KOH+0.5 M urea solution.For the UOR||HER system,CoNi@CN-CoNiMoO only needs 1.58 V at 500 mA cm-2 and shows good stability.Density functional theory calculation suggests that the strong electronic interaction at the interface between NiCo alloy and N-doping-carbon layers can optimize the adsorption/desorption energy of UOR/HER intermediates and accelerate the water dissociation,which can expedite urea decomposition and Volmer step,thus increasing the UOR and HER activity,respectively.This work provides a new solution to design UOR/HER catalysts for H2 production through urea-assisted water electrolysis.

Fault Diagnosis and Separation for a Distributed Rotary-laser Scanning System

The wMPS is a laser-based measurement system used for large scale metrology.However,it is susceptible to external factors such as vibrations,which can lead to unreliable measurements.This paper presents a fault diagnosis and separation method which can counter this problem.To begin with,the paper uses simple models to explain the fault diagnosis and separation methods.These methods are then mathematically derived using statistical analysis and the principles of the wMPS.A comprehensive solution for fault diagnosis and separation is proposed,considering the characteristics of the wMPS.The effectiveness of this solution is verified through experimental observations.It can be concluded that this approach can detect and separate false observations,thereby enhancing the reliability of the wMPS.

N‑Doped Graphene‑Decorated NiCo Alloy Coupled with Mesoporous NiCoMoO Nano‑sheet Heterojunction for Enhanced Water Electrolysis Activity at High Current Density

Developing highly effective and stable non-noble metalbased bifunctional catalyst working at high current density is an urgent issue for water electrolysis(WE).Herein,we prepare the N-doped graphene-decorated NiCo alloy coupled with mesoporous NiCoMoO nano-sheet grown on 3D nickel foam(NiCo@C-NiCoMoO/NF)for water splitting.NiCo@C-NiCoMoO/NF exhibits outstanding activity with low overpotentials for hydrogen and oxygen evolution reaction(HER:39/266 mV;OER:260/390 mV)at±10 and±1000 mA cm^(−2).More importantly,in 6.0 M KOH solution at 60℃ for WE,it only requires 1.90 V to reach 1000 mA cm−2 and shows excellent stability for 43 h,exhibiting the potential for actual application.The good performance can be assigned to N-doped graphene-decorated NiCo alloy and mesoporous NiCoMoO nano-sheet,which not only increase the intrinsic activity and expose abundant catalytic activity sites,but also enhance its chemical and mechanical stability.This work thus could provide a promising material for industrial hydrogen production.

Three-Phase Heterojunction NiMo-Based Nano-Needle for Water Splitting at Industrial Alkaline Condition

Constructing heterojunction is an effective strategy to develop high-performance non-preciousmetal-based catalysts for electrochemical water splitting(WS).Herein,we design and prepare an N-doped-carbon-encapsulated Ni/MoO_(2) nano-needle with three-phase heterojunction(Ni/MoO_(2)@CN)for accelerating the WS under industrial alkaline condition.Density functional theory calculations reveal that the electrons are redistributed at the three-phase heterojunction interface,which optimizes the adsorption energy of H-and O-containing intermediates to obtain the best ΔG_(H*) for hydrogen evolution reaction(HER)and decrease the ΔG value of ratedetermining step for oxygen evolution reaction(OER),thus enhancing the HER/OER catalytic activity.Electrochemical results confirm that Ni/MoO_(2)@CN exhibits good activity for HER(ƞ_(-10)=33 mV,ƞ_(-1000)=267 mV)and OER(ƞ_(10)=250 mV,ƞ_(1000)=420 mV).It shows a low potential of 1.86 V at 1000 mA cm^(−2) for WS in 6.0 M KOH solution at 60℃ and can steadily operate for 330 h.This good HER/OER performance can be attributed to the three-phase heterojunction with high intrinsic activity and the self-supporting nano-needle with more active sites,faster mass diffusion,and bubbles release.This work provides a unique idea for designing high efficiency catalytic materials for WS.

Enhancement of oxygen reduction activity and stability via introducing acid-resistant refractory Mo and regulating the near-surface Pt content

Although Pt Ni catalyst possesses good oxygen reduction activity, its poor stability is the main obstacle for the commercialization of proton exchange membrane fuel cells(PEMFCs). In this work, we introduce the acid-resistant refractory Mo to enhance the structure stability and modify the electronic structure of Pt in the prepared PtNi catalyst, improving the catalytic activity for oxygen reduction reaction(ORR). In addition, near-surface Pt content in the nanoparticle is also optimized to balance the ORR activity and stability. The electrochemical results show that the alloy formed by Mo and Pt Ni is obviously more stable than the PtNi alloy alone, because the acid-resistant Mo and its oxides effectively prevent the dissolution of Pt. Especially, the Pt3 Ni3 MoN/C exhibits the optimal ORR catalytic performance in O2-saturated 0.1 mol L^(-1) HClO4 aqueous solutions, with mass activity(MA) of 900 m A mg^(-1) Pt at 0.90 V vs. RHE, which is 3.75 times enhancement compared with the commercial Pt/C(240 mA mg^(-1) Pt). After 30 k accelerated durability tests, its MA(690 m A mg^(-1) Pt) is still 2.88 times higher than the pristine Pt/C. This study thus provides a valuable method to design stable ORR catalysts with high efficiency and has great significance for the commercialization of PEMFCs.

Bifunctional interstitial phosphorous doping strategy boosts platinum-zinc alloy for efficient ammonia oxidation reaction and hydrogen evolution reaction

It is still a lack of bifunctional catalysts for ammonia oxidation reaction(AOR)and hydrogen evolution reaction(HER)due to their different reaction mechanisms.In this work,P is doped into PtZn alloy by calcination with NaH_(2)PO_(2) as P source to induce the lattice tensile strain of Pt and the electronic interaction between P and Zn,which optimizes the AOR and HER activity simultaneously.The sample with the optimal P content can drive the AOR peak current density of 293.6 mA·mgPt^(-1),which is almost 2.7 times of Pt.For HER,the overpotential at^(-1)0 mA·cm^(-2) is only 23 mV with Tafel slope of 34.1 mV·dec^(-1).Furthermore,only 0.59 V is needed to obtain 50 mA·mgPt^(-1) for ammonia electrolysis under a two-electrode system.Therefore,this work shows an ingenious method to design bifunctional catalysts for ammonia electrolysis.

B and Fe co-doped Co_(2)P hollow nanocubes for nitrate electroreduction to ammonia

Nitrate(NO_(3)^(−))electroreduction reaction(NO_(3)^(−)RR)provides an attractive and sustainable route for NO_(3)^(−)pollution mitigation or energy-saved ammonia(NH3)synthesis.In this work,high-quality B and Fe co-doped Co_(2) P hollow nanocubes(B/Fe-Co_(2) P HNCs)are successfully synthesized though simultaneous boronation-phosphorization treatment,which reveal outstanding selectivity,activity,stability for the NO_(3)^(−)to NH_(3) conversion in neutral electrolyte because of big surface area,fast mass transport,superhydrophilic surface,and optimized electronic structure.B/Fe-Co_(2) P HNCs can achieve the high NH3 yield rate(22.67 mg h^(−1) mg_(cat)^(−1))as well as Faradaic efficiency(97.54%)for NO_(3)^(−)RR,greatly outperforming most of non-precious metal based NO_(3)^(−)RR electrocatalysts.

Te-doped Fe_(3)O_(4) flower enabling low overpotential cycling of Li-CO_(2) batteries at high current density

Li-CO_(2)batteries(LCBs)suffer from high overpotentials caused by sluggish CO_(2)reaction kinetics.This work designs a Te-doped Fe_(3)O_(4)(Te-Fe_(3)O_(4))flower-like microsphere catalyst to lower the overpotential and improve the reversibility of LCBs.Experimental results reveal that Te doping modifies the electronic structure of Fe_(3)O_(4)and reduces the overpotential.The stable Te-O bond between Te and C_(2)O^(2-)_(4)could effectively inhibit the dispro-portionation reaction of the latter,enabling the Te-Fe_(3)O_(4)cathodes to exhibit a remarkable capacity(9485 mAh g^(-1))and a long cycling life(155 cycles)with an overpotential of 1.21 V and an energy efficiency of about 80%at a high current density(2000 mA g^(-1)).Through the interaction between Te and Li_(2)C_(2)O_(4)to inhibit the dispro-portionation reaction,this work successfully achieves long-term cycling of LCBs with low overpotential at high current density.

NiCo alloy nanoparticles anchored on mesoporous Mo_(2)N nanosheets as efficient catalysts for 5-hydroxymethylfurfural electrooxidation and hydrogen generation

Construction of highly active and stable bifunctional catalysts for 5-hydroxymethylfurfural oxidation reaction(HMFOR)and hydrogen evolution reaction(HER)is meaningful but remains a challenge.Herein,the NiCo–Mo_(2)N heterostructure nanosheets catalyst with excellent HMFOR/HER performance is obtained by a simple hydrothermal and calcination method.The heterogeneous interface between NiCo and Mo_(2)N induces electron redistribution,regulating the electronic structure of the catalyst and thus optimizing the adsorption/desorption behavior of HMFOR/HER intermediates.Consequently,NiCo–Mo_(2)N/NF exhibits superior catalytic activity with a potential of 1.14 V_(RHE)/−17 mV_(RHE)(HMFOR/HER)at±10 mA cm^(−2),and the HMF conversion rate,FDCA yield,and Faradaic efficiency(FE)are∼100%,99.98%,and 98.65%,respectively.Besides,it only requires a low voltage of 1.36 V to achieve 100 mA cm^(−2)for HMFOR-assisted H2 production.This study provides a strategy for the development of efficient bifunctional catalysts for sustainable production of high value-added products and hydrogen.

Modulating metal-support interaction between Pt_(3)Ni and unsaturated WOx to selectively regulate the ORR performance

Tuning strong metal-support interaction between Pt-based alloys and metal oxides is an effective strategy for modulating the performance of oxygen reduction reaction(ORR).Herein,Pt_(3)Ni alloy anchored on WO_(x) with different content of oxygen vacancies is synthesized,and the effect of unsaturated WO_(x) on ORR activity/stability is revealed.Electrochemical results indicate that ORR activity is positively correlated with oxygen vacancy concentration,while durability presents the opposite trend.Density functional theory(DFT)calculation results suggest that controlling the content of oxygen vacancies can usefully adjust the charge redistribution between Pt_(3)Ni and WO_(x),which can optimize the adsorption/activation of reactants,thus obtaining good ORR activity.This study uncovers the effect of unsaturated WO_(x) on ORR performance for Pt-based alloys and provides a promising strategy to design efficient and stable ORR catalysts.

Synergized oxygen vacancies with Mn_(2)O_(3)@CeO_(2)heterojunction as high current density catalysts for Li-O_(2)batteries

The application of Li-O_(2)batteries(LOBs)with ultra-high theoretical energy density is limited due to the slow redox kinetics and serious side reactions,especially in high-rate cycles.Herein,CeO_(2)is constructed on the surface of Mn_(2)O_(3)through an interface engineering strategy,and Mn_(2)O_(3)@CeO_(2)heterojunction with good activity and stability at high current density is prepared.The interfacial properties of catalyst and formation mechanism of Li_(2)O_(2)are deeply studied by density functional theory(DFT)and experiments,revealing the charge-discharge reaction mechanism of LOBs.The results show that the strong electron coupling between Mn_(2)O_(3)and CeO_(2)can promote the formation of oxygen vacancies.Heterojunction combined with oxygen vacancy can improve the affinity for O_(2)and LiO_(2)reaction intermediates,inducing the formation of thin-film Li_(2)O_(2)with low potential and easy decomposition,thus improving the cycle stability at high current density.Consequently,it achieved a high specific capacity of 12545 at 1000 mA g^(-1)and good cyclability of 120 cycles at 4000 mA g^(-1).This work thus sheds light on designing efficient and stable catalysts for LOBs under high current density.

Highly active bifunctional catalyst: Constructing FeWO_(4)-WO_(3) heterostructure for water and hydrazine oxidation at large current density

Developing high performance anode catalysts for oxygen evolution reaction (OER) and hydrazine oxidation reaction (HzOR) at large current density is an efficient pathway to produce hydrogen. Herein, we synthesize a FeWO_(4)-WO_(3) heterostructure catalyst growing on nickel foam (FeWO_(4)-WO_(3)/NF) by a combination of hydrothermal and calcination method. It shows good catalytic activity with ultralow potentials for OER (ζ_(10) = 1.43 V, ζ_(1.000) = 1.56 V) and HzOR (ζ_(10) = −0.034 V, ζ_(1.000) = 0.164 V). Moreover, there is little performance degradation after being tested for _(10)0 h at 1,000 (OER) and _(10)0 (HzOR) mA·cm−2, indicating good stability. The superior performance could be attributed to the wolframite structure and heterostructure: The former provides a high electrical conductivity to ensure the electronic transfer capability, and the later induces interfacial electron redistribution to enhance the intrinsic activity and stability. The work offers a brand-new way to prepare good performance catalysts for OER and HzOR, especially at large current density.