Highly efficient and selective photocatalytic dehydrogenation of benzyl alcohol for simultaneous hydrogen and benzaldehyde production over Ni-decorated Zn_(0.5)Cd_(0.5)S solid solution

Photocatalytic conversion of solar energy into hydrogen and high value-added fine chemicals has attracted increasing attention. Herein, we demonstrate an efficient photocatalytic system for simultaneous hydrogen evolution and benzaldehyde production by dehydrogenation of benzyl alcohol over Nidecorated Zn_(0.5)Cd_(0.5)S solid solution under visible light. The photocatalytic system shows an excellent hydrogen production rate of 666.3 μmol h^(-1) with high stability. The optimal apparent quantum yield of52.5% is obtained at 420 nm. This noble-metal-free photocatalytic system displays much higher activity than pure Zn_(0.5)Cd_(0.5)S and Pt-loaded Zn_(0.5)Cd_(0.5)S solid solution. Further studies reveal that the metallic Ni nanocrystals play an important role in accelerating the separation of photogenerated charge carriers and the subsequent cleavage of α-C–H bond during dehydrogenation of benzyl alcohol.

Integrating non-precious-metal cocatalyst Ni_3N with g-C_3N_4 for enhanced photocatalytic H_2 production in water under visible-light irradiation

Photocatalytic H2 production via water splitting in a noble-metal-free photocatalytic system has attracted much attention in recent years.In this study,noble-metal-free Ni3N was used as an active cocatalyst to enhance the activity of g-C3N4 for photocatalytic H2 production under visible-light irradiation(λ>420 nm).The characterization results indicated that Ni3N nanoparticles were successfully loaded onto the g-C3N4,which accelerated the separation and transfer of photogenerated electrons and resulted in enhanced photocatalytic H2 evolution under visible-light irradiation.The hydrogen evolution rate reached^305.4μmol h^-1 g^-1,which is about three times higher than that of pristine g-C3N4,and the apparent quantum yield(AQY)was^0.45%atλ=420.Furthermore,the Ni3N/g-C3N4 photocatalyst showed no obvious decrease in the hydrogen production rate,even after five cycles under visible-light irradiation.Finally,a possible photocatalytic hydrogen evolution mechanism for the Ni3N/g-C3N4 system is proposed.

Metal-free graphene quantum dots photosensitizer coupled with nickel phosphide cocatalyst for enhanced photocatalytic hydrogen production in water under visible light

Photocatalytic hydrogen(H2)evolution is a promising approach for future sustainable energy utilization.However,it is still a great challenge to develop efficient and stable metal‐free photocatalysts with broadband solar absorption in the visible region for H2 production.Metal‐free graphene quantum dot(GQD)is an emerging candidate for this purpose because of its good water‐solubility and tunable band gap.On the other hand,metal phosphides(Ni2P,Co2P,etc)have been demonstrated as novel noble‐metal‐free cocatalysts for water splitting,which can efficiently separate electron‐hole pairs and enhance the photocatalytic activities.Herein,we report for the first time on the use of OH‐functionalized GQDs(OH‐GQDs)photosensitizer coupled with Ni2P nanoparticles for photocatalytic H2 production withλ>420 nm light.The H2 production rate is^94 times higher than that of bare OH‐GQDs,which is even comparable to that of OH‐GQDs with 1.0 wt%Pt cocatalyst.This enhancement is probably due to the semiconductor‐cocatalyst interface interaction between Ni2P and OH‐GQDs to facilitate efficient charge transfer process.

Integrating noble-metal-free NiS cocatalyst with a semiconductor heterojunction composite for efficient photocatalytic H_2 production in water under visible light

Photocatalytic water splitting is an economical and sustainable pathway to use solar energy for large‐scale H2production.We report a highly efficient noble‐metal‐free photocatalyst formed by integrating amorphous NiS with a CdS nanorods(NRs)/ZnS heterojunction material for photocatalytic H2production in water under visible light irradiation(?>420nm).The results show that the photocatalytic H2production rate reaches an optimal value of up to574μmol·h–1after the loading of NiS,which is more than38times higher than the catalytic activity of pure CdS NRs.The average apparent quantum yield is^43.2%during5h of irradiation by monochromatic420nm light.The present study demonstrates the advantage of integration strategies to form not only semiconductor heterojunctions but also photocatalyst‐cocatalyst interfaces to enhance the catalytic activity for photocatalytic H2production.

A molecular cobaloxime cocatalyst and ultrathin FeOOH nanolayers co-modifiedBiVO_(4) photoanode for efficient photoelectrochemical water oxidation

BiVO_(4) has been attracting a lot of interest in photoelectrochemical (PEC) water oxidation due to its efficient solar absorption and appropriate band positions.So far,sluggish water oxidation kinetics and fast photogenerated charge recombination still hinder the PEC performance ofBiVO_(4) .In this study,a novel PEC photoanode was designed by depositing ultrathin FeOOH nanolayers on the surface of nanoporousBiVO_(4) electrode,followed by modification with a cobaloxime (Co(dmgH)_(2)(4-COOH-py)Cl) molecular cocatalyst.Under irradiation of a 100 mW cm^(-2)(AM 1.5G) Xe lamp,the photocurrent density of the cobaloxime/FeOOH/BiVO_(4) composite photoanode reached 5.1 mA cm^(-2)at 1.23 V vs.RHE in 1.0 M potassium borate buffer solution (pH=9.0).The onset potential of the optimal cobaloxime/FeOOH/BiVO_(4) photoanode exhibited a 460 m V cathodic shift relative to bareBiVO_(4) .In addition,the surface charge injection efficiency of the composite photoanode reached~80%at 1.23 V vs.RHE and the incident photon-to-current efficiency (IPCE) reached~88%at 420 nm.

Self-supported Ni2P nanosheets on low-cost three-dimensional Fe foam as a novel electrocatalyst for efficient water oxidation

Electrochemical water splitting into hydrogen and oxygen is a promising strategy for future renewable energy conversion devices.The oxygen evolution reaction(OER)is considered as the bottleneck reaction in an overall water splitting system because it involves 4e- and 4H+ transfer processes.Currently,it is highly desirable to explore low-cost alternative catalysts for OER at ambient conditions.Herein,we report for the first time that nickel phosphide(Ni2P)nanosheets can be facilely grown on Fe foam(FF)as an efficient electrocatalyst for OER with excellent durability and catalytic activity under alkaline conditions.To reach a current density of 10 m A/cm2,the Ni2P-FF catalyst required a low overpotential of only 198 mV for OER.The catalyst’s high OER activity and durability were well maintained at a high current density.The required overpotentials were only 267 and 313 mV to achieve the current densities of 100 and 300 m A/cm2,respectively.The combination of low-cost Fe foam with Ni2P provides a promising low-cost catalyst for large-scale application of electrocatalytic water splitting.

Facile deposition of cobalt oxide based electrocatalyst on low-cost and tin-free electrode for water splitting

Facile deposition of a water-splitting catalyst on low-cost electrode materials could be attractive for hydrogen production from water and solar energy conversion. Herein we describe fast electrodeposition of cobalt-based water oxidation catalyst （Co-WOC） on simple graphite electrode for water splitting, The deposition process is quite fast, which reaches a plateau in less than 75 min and the final ctLrrent density is -1.8 mA/cm2 under the applied potential of 1.31 V at pH --7.0. The scanning electron microscopy （SEM） study shows the formation of nanometer-sized particles （10-100 nm） on the surface of the electrode after only 2 min and micrometer-sized particles （2-5/zm） after 90 rain of electrolysis. X-ray photoelectron spectroscopy （XPS） data demonstrate the as-synthesized ex-situ catalyst mainly contains Co2＋ and Co3＋ species incorporating a substantial amount of phosphate anions. These experiments suggest that cost-efficient cobalt oxide materials on graphite exhibit alluring ability for water splitting, which might provide a novel method to fabricate low-cost devices for electrochemical energy storage.

A strained π-extended[10]cycloparaphenylene carbon nanoring

Herein,we report the facile synthesis of a highly strained hexabenzocoronene-containing carbon nanoring,cyclo[4]-paraphenylene[2]-2,11-hexabenzocoronenylene([4,2]CPHBC),as the segment of a[10,10]single-walled carbon nanotube([10,10]SWNT).[4,2]CPHBC was synthesized based on the platinummediated assembly of diborylbiphenyl and diborylhexabenzocoronene,forming a tetranuclear platinum complex,followed by reductive elimination.This nanoring molecule was confirmed by NMR and HRMS,and its photophysical properties were studied using steady-state and time-resolved spectroscopies.Moreover,the selective supramolecular host-guest interaction between[4,2]CPHBC and C_(60) was also investigated.

Selective synthesis and physical properties of a bismacrocycle:Cycloparaphenylene-pillar[5]arene

Macrocyclic materials have attracted much attention due to their particular chemical and physical properties.Herein we report the precise synthesis and characterization of a new bismacrocycle structure base on cycloparaphenylene(CPP)and pillar[5]arene,named cycloparaphenylene-pillar[5]arenes(CPPn[5]).The bismacrocycle was fully characterized by NMR and HR-MS.The photophysical properties of CPPn[5]were investigated by UV–vis,and the maximum absorption peak was located at 331 nm,which was consistent with density functional theory(DFT)calculations.The fluorescence spectrum was further studied and the emission peak was maximized at 458 nm.The computational results indicate the strain energy of CPPn[5]is 27.80 kcal/mol and the HOMO-LUMO gap is 3.39 eV Notably,CPPn[5]showed interesting supramolecular properties.

Pomegranate-like C_(60)@cobalt/nitrogen-codoped porous carbon for high-performance oxygen reduction reaction and lithium-sulfur battery

Porous carbon materials play essential roles in electrocatalysis and electrochemical energy storage.It is of significant importance to rationally design and tune their porous structure and active sites for achieving high electrochemical activity and stability.Herein,we develop a novel approach to tune the morphology of porous carbon materials(PCM)by embedding fullerene C_(60),achieving improved performance of oxygen reduction reaction(ORR)and lithium-sulfur(Li-S)battery.Owing to the strong interaction between C_(60)and imidazole moieties,pomegranate-like hybrid of Ow-embedded zeolitic imidazolate framework(ZIF-67)precursor is synthesized,which is further pyrolyzed to form C_(60)-embedded cobalt/nitrogen-codoped porous carbon materials(abbreviated as C_(60)@Co-N-PCM).Remarkably,the unique structure of C_(60)@Co-N-PCM offers excellent ORR electrocatalytic activity and stability in alkaline solutions,outperforming the commercial Pt/C(20 wt.%)catalyst.Besides,C_(60)@Co-N-PCM as a novel cathode delivers a high specific capacity of-900 mAh·g^(-1) at 0.2 C rate in Li-S batteries,which is superior to the pristine ZIF-67-derived PCM without embedding C_(60).

Synthesis of an all-carbon conjugated polymeric segment of carbon nanotubes and its application for lithium-ion batteries

The synthesis and potential applications of nanocarbon materials have attracted much attention in recent years.Herein,we report the design and synthesis of a novel all-carbon conjugated polymeric segment of single-walled carbon nanotubes(poly(cyclo-para-phenylene)(PCPP))and its first application as an anode material for lithium-ion batteries.The as-synthesized PCPP was characterized by Raman spectroscopy,Fourier transform infrared(FTIR),and other spectroscopies.The electrochemical characterization results show the suitability of PCPP as an anode material for lithium-ion batteries.Theoretical calculations indicate the unique structural and physical properties of PCPP.The realization of PCPP expands the scope of bottom-up synthesis of uniform carbon nanotube segments and their potential applications as new materials for lithium-ion batteries.

Nitrogen photofixation on holey g-C3N4 nanosheets with carbon vacancies under visible-light irradiation

Nitrogen photo fixation using g-C3N4-based photocatalysts have attracted abundant of attentions recently.Herein,in this study,holey g-C3N4(HGCN)nanosheets possess a good deal of carbon vacancies were prepared by means of thermally treating bulk g-C3 N4(BGCN)under an NH3 atmosphere.Characterization analysis revealed that the as-synthesized sample have identical crystal structure,la rger BET specific surface area,stronger reduction capability,and higher photogene rated charge carrier separation rate than that of BGCN.These properties may contribute to enhance the nitrogen photofixation activity.It was also found that the rate of NH4^+production for N2 photofixation of HGCN sample reached^25.54 mg L^-1 h^-1 g(cat)^-1,which is approximately^5.87 times higher than that of BGCN sample under optimal reactive conditions.Moreover,a plausible mechanism of HGCN for nitrogen photofixation process was illuminated in detail.