Re-usable Cd_(0.9)Zn_(0.1)S-ZnO@C/PVDF piezo-photocatalytic film with exceptional hydrogen evolution capability triggered by the synergetic advantages of piezoelectricity and S-Scheme heterojunction

Piezoelectric materials have advantages of fine-tuning photocatalytic performance through harvesting mechanical energy and open a new avenue in facilitating green catalytic reaction.Herein,polyvinylidene fluoride(PVDF),a flexible piezoelectric material,was introduced to synthesize a novel Cd_(0.9)Zn_(0.1)S-ZnO@C/PVDF(CZS-ZO@C/PVDF)piezo-photocatalytic film by spin coating and immersion phase conversion method.Benefiting from the piezoelectricity of PVDF and the internal electric field(IEF)of CZS-ZO@C Step-scheme(S-Scheme)heterojunction,CZS-ZO@C/PVDF was able to induce a hydrogen generation rate of 34.9 mmol g^(−1)h^(−1)activated by ultrasound and visible light(U-L),which is∼17.5 times of Cd_(0.9)Zn_(0.1)S/PVDF(CZS/PVDF)and∼7.4 times of the photocatalysis rate activated by visible light only(L).Piezoelectric measurements and COMSOL simulation illustrated the excellent piezoelectricity of CZS-ZO@C/PVDF film,which exhibits a piezoelectric coefficient(d33)of 9.9 pm V−1 and a piezoelectric potential of 874 mV(under 0.5 MPa).The reaction mechanism for the exceptional piezo-photocatalytic performance was finally disclosed through density functional theory(DFT)calculation and electrochemical tests.This study enriches the application scope of piezoelectric materials in sustainable energy catalysis and provides a new direction to develop efficient piezoelectric photocatalysts.

Rational construction of CuFe_(2)O_(4)@C/Cd_(0.9)Zn_(0.1)S S-scheme heterojunction photocatalyst for extraordinary photothermal-assisted photocatalytic H_(2) evolution

Rational design of photocatalyst to maximize the use of sunlight is one of the issues to be solved in photocatalysis technology.In this study,the CuFe_(2)O_(4)@C/Cd_(0.9)Zn_(0.1)S(CFO@C/CZS)S-scheme photocatalyst with photothermal effect was synthesized by ultrasonic self-assembly combined with calcination.The dark CFO@C absorbed visible light and partly converted into heat to promote the hydrogen evolution reaction.The presence of heterojunctions inhibited the photogenerated electron-hole recombination.The graphite-carbon layer provided a stable channel for electron transfer,and the presence of magnetic CFO made recycle easier.Under the action of photothermal assistance and heterojunction,the hydrogen evolution rate of the optimal CFO@C/CZS was 80.79 mmol g^(-1) h^(-1),which was 2.55 times and 260.61 times of that of pure CZS and CFO@C,respectively.Notably,the composite samples also exhibit excellent stability and a wide range of environmental adaptability.Through experimental tests and first-principles simulation calculation methods,the plausible mechanism of photoactivity enhancement was proposed.This work provided a feasible strategy of photothermal assistance for the development of heterojunction photocatalysts with distinctive hydrogen evolution.

High-Performance Na-Ion Storage of S-Doped Porous Carbon Derived from Conjugated Microporous Polymers

Na-ion batteries(NIBs)have attracted considerable attention in recent years owing to the high abundance and low cost of Na.It is well known that S doping can improve the electrochemical performance of carbon materials for NIBs.However,the current methods for S doping in carbons normally involve toxic precursors or rigorous conditions.In this work,we report a creative and facile strategy for preparing S-doped porous carbons(SCs)via the pyrolysis of conjugated microporous polymers(CMPs).Briefly,thiophene-based CMPs served as the precursors and doping sources simultaneously.Simple direct carbonization of CMPs produced S-doped carbon materials with highly porous structures.When used as an anode for NIBs,the SCs exhibited a high reversible capacity of 440 mAh g?1 at 50 mA g?1 after 100 cycles,superior rate capability,and excellent cycling stability(297 mAh g?1 after 1000 cycles at 500 mA g?1),outperforming most S-doped carbon materials reported thus far.The excellent performance of the SCs is attributed to the expanded lattice distance after S doping.Furthermore,we employed ex situ X-ray photoelectron spectroscopy to investigate the electrochemical reaction mechanism of the SCs during sodiation-desodiation,which can highlight the role of doped S for Na-ion storage.

Coralline-like Ni_(2)P decorated novel tetrapod-bundle Cd_(0.9)Zn_(0.1)S ZB/WZ homojunctions for highly efficient visible-light photocatalytic hydrogen evolution

In this study,Ni_(2)P-Cd_(0.9)Zn_(0.1)S(NPCZS)composites were synthesized by coupling tetrapod bundle Cd_(0.9)Zn_(0.1)S(CZS)and coralline-like Ni_(2)P(NP)via a simple calcination method.CZS shows outstanding activity in photocatalytic hydrogen evolution(1.31 mmol h^(‒1)),owing to its unique morphology and heterophase homojunctions(ZB/WZ),which accelerate the separation and transfer of photogenerated charges.After coupling with NP,the photoactivity of NPCZS was enhanced,and the maximum hydrogen evolution rate of 1.88 mmol h^(‒1)was reached at a NP content of 12 wt%,which was 1.43 times higher than that of pure CZS.The experimental results of the photocatalytic activity,viz.photoluminescence spectra,surface photovoltage spectra,and electrochemical test showed that the enhanced photoactivity of NPCZS should be attributed to the synergistic effects of the novel tetrapod-bundle morphology,heterophase homojunctions,and decoration of the NP co-catalyst.Moreover,the as-prepared NPCZS composites exhibited excellent photostability and recyclability.Herein,we propose a possible mechanism for the enhanced photocatalytic activity.

One stone,three birds:up-conversion,photothermal and p-n heterojunction to boost BiOBr:Yb^(3+),Er^(3+)/Cu_(3)Mo_(2)O_(9) full spectrum photodegradation

Broadening spectral response range to realize the full spectrum photocatalysis is crucial to develop photocatalysts with satisfactory light-energy conversion ability.A full-spectrum driven p-n heterojunction photocatalytic system was rationally designed through introducing the Er^(3+)/Yb^(3+)co-doped BiOBr with up-conversion effect as the collector of near infrared light and photocatalysts substrate.Meanwhile,Cu_(3)Mo_(2)O_(9) with the photothermal effect as a heat source to accelerate the reaction at the surface through absorbing the near infrared light.The photocatalytic activity of BiOBr:Yb^(3+),Er^(3+)/Cu3Mo2O9 composite was markedly strengthened under visible and near infrared light irradiation,and the BiOBr:Yb^(3+),Er^(3+)/Cu_(3)Mo_(2)O_(9)-5 composite displayed the optimal photodegradation activities for 0.03372 min^(-1) and 0.058 h^(-1),being 2.3-folds and 2.4-folds than that of pure BiOBr:Yb^(3+),Er^(3+)under the visible and near infrared light,respectively.The position of doped ions(Yb^(3+)and Er^(3+))in BiOBr:Yb^(3+),Er^(3+)was determined from the X-ray absorption fine structure spectra.And the reasonable mechanism of p-n heterojunction was proposed base on the results of experimental and density functional theory calculation.This work provides a rational strategy for the design and development of full-spectrum heterojunction photocatalysts with the up-conversion and photothermal effects to increase the photocatalytic performance.

Coupling effects of Zn single atom and high curvature supports for improved performance of CO_(2) reduction

Single-atom catalysts(SACs)have emerged as one of the most competitive catalysts toward a variety of important electrochemical reactions,thanks to their maximum atom economy,unique electronic and geometric structures.However,the role of SACs supports on the catalytic performance does not receive enough research attentions.Here,we report an efficient route for synthesis of single atom Zn loading on the N-doped carbon nano-onions(ZnN/CNO).ZnN/CNO catalysts show an excellent high selectivity for CO_(2) electro-reduction to CO with a Faradaic efficiency of CO(FECO)up to 97%at -0.47 V(vs.reversible hydrogen electrode,RHE)and remarkable durability without activity decay.To our knowledge,ZnN/CNO is the best activity for the Zn based catalysts up to now,and superior to single atom Zn loading on the two-dimensional planar and porous structure of graphene substrate,although the graphene with larger surface area.The exact role of such carbon nano-onions(CNO)support is studied systematically by coupling characterizations and electrochemistry with density functional theory(DFT)calculations,which have attributed such good performance to the increased curvature.Such increased curvature modifies the surface charge,which then changes the adsorption energies of key intermediates,and improves the selectivity for CO generation accordingly.

SnFe_(2)O_(4)/ZnIn_(2)S_(4)/PVDF piezophotocatalyst with improved photocatalytic hydrogen production by synergetic effects of heterojunction and piezoelectricity

The polarized electric field inside piezoelectric materials has been proven to be a promising technique to boost photogenerated charge separation.Herein,a novel flexible SnFe_(2)O_(4)/ZnIn_(2)S_(4)/polyvinylidene fluoride((CH2CF2)_(n),PVDF)(P-SZ)film piezophotocatalyst was successfully synthesized by combining PVDF,an organic piezoelectric material,with a SnFe_(2)O_(4)/ZnIn_(2)S_(4)(SFO/ZIS)type II heterojunction photocatalyst.The hydrogen evolution rate of SFO/ZIS heterojunction with a SFO content of 5%is about 846.79μmol·h^(−1)·g^(−1),which is 3.6 times that of pristine ZIS.Furthermore,after being combined with PVDF,the optimum hydrogen evolution rate of P-SZ is about 1652.7μmol·h^(−1)·g^(−1)in the presence of ultrasound,which exceeds that of 5%SFO/ZIS by an approximate factor of 2.0.Based on experimental results,the mechanism of the improved photocatalytic performance of P-SZ was proposed on the basis of the piezoelectric field in PVDF and the formed heterojunction between SFO and ZIS,which effectively boosted the separation of photoinduced charges.This work provides an efficient strategy for multi-path collection and utilization of natural solar and vibrational energy to enhance photoactivity.