From Homogeneous To Heterogeneous,Chemical Activity And Stability Of Organic Molecules As New Energy Materials

The unprecedented high level of atmospheric CO₂ is supposed to be the origin of global warming and many other climate abnormalities.Controlling CO₂ level has now become a broad consensus among global communities,and actions are urgently needed to be taken at this moment.Electro-reduction of CO₂ is an effective method that can simultaneously consume excessive CO₂ and produce value-added carbon product.Catalyst of high efficiency is at the heart of electro-reduction.For CO₂ electro-reduction,transition metal functionalized porphyrin?TMP?is an important kind of organic catalysts.However,the reduction mechanism with TMP remains controversial.Through the study of often-neglected interaction between aqueous environment and catalyst in the pre-reduction stage.We find that,in contrary to previous results,the protonation actually happens before CO₂ is activated.Based on this novel protonation mechanism,we demonstrate the different producing rate-pH correlations for the formation of CO and methane,in good agreement with the available experimental observations.Our results reveal how the synergetic effect of pH and potential modifies protonation mechanism,affects producing rate and product spectrum.We point out limiting factors to the CO₂ reduction,and possible solutions are provided,upon which,more effective methods can be developed to promote the design of TMP catalyst in future practices.Another long-standing issues that prohibits large-scale CO₂ reutilization is the low aqueous CO₂ solubility and the incurring inefficient mass transport of CO₂.Herein,we suggest a feasible way to promote the CO₂ reutilization by integrating the storage and reduction,with a new covalent organic framework?COF?series constituted by cobalt-phthalocyanine and boronic acid linker,Co-Pc-PBBA.Inspired by the extremely high CO₂ concentration in solid gas sorbent,we seek to integrate the storage function onto the reduction main body.We demonstrate the Co-Pc-PBBA to be a promising candidate as CO₂ reduction catalyst due to the synergy of storage and catalysis.Owing to the integration of storage function,a 97.7 times higher CO₂ concentration can be achieved in Co-Pc-PBBA than in aqueous environment at298K,normal pressure.The increased CO₂ concentration would lower the overpotential from0.39 V to 0.27 V and increase the reaction rate by 97.7 times,both to be significant improvements compared to recent reports.We also suggest an integrated electrode design,upon which,future practical improvement can be expected.Industrious CO₂ reduction process would be meaningless if clean energy not used.Hybrid perovskite has now emerged as the star of the 3^rd generation solar cells for harvesting solar energy.However,the poor long-term stability of PSC still holds the biggest challenge to its commercialization.Especially,water/moisture poses the most damaging factor.Researchers have attempted different synthesis routes to elongate PSC's service time.However,such methods often generate discrete and puzzling results,an in-depth and consistent understanding of the relation between PSC's long-term stability and its growth condition has not been established yet.Starting from the microscopic model of water molecule movement on PSC surface,we firstly confirmed the vertical penetration to be the limiting step in water diffusion process,which defines the overall decomposition rate of PSC.While,the macroscopic growth condition of PSC affects the formation of point defects on surface.We find the major point defects on surface(V_MAA and V_I-?)can decrease the energy barrier of the limiting penetration step remarkably,and thus accelerate the degradation.Importantly,the devastating effect of surface point defect can be largely alleviated by tuning the growth condition during synthesis so as to prevent the formation of detrimental defect types,which offers new ideas/options to control the quality of PSC for real use.