Integration of morphology and electronic structure modulation on cobalt phosphide nanosheets to boost photocatalytic hydrogen evolution from ammonia borane hydrolysis

The controllable and safe hydrogen storage technologies are widely recognized as the main bottleneck for the accomplishment of sustainable hydrogen energy.Ammonia borane(AB)has regarded as a competitive candidate for chemical hydrogen storage.However,developing efficient yet high-performance catalysts towards hydrogen evolution from AB hydrolysis remains an enormous challenge.Herein,cobalt phosphide nanosheets are synthesized by a facile salt-assisted along with low-temperature phosphidation strategy for simultaneously modulating its morphology and electronic structure,and function as hydrogen evolution photocatalysts.Impressively,the Co_(2)P nanosheets display extraordinary performance with a record high turnover frequency of 44.9 min^(-1),outperforming most of the noble-metal-free catalysts reported to date.This remarkable performance is attributed to its desired nanosheets structure,featuring with high specific surface area,abundant exposed active sites,and short charge diffusion paths.Our findings provide a novel strategy for regulating metal phosphides with desired phase structure and morphology for energy-related applications and beyond.

Pathways of liquefied petroleum gas pyrolysis in hydrogen plasma:A density functional theory study

A density functional theory （DFT） study has been conducted in this work to investigate the pyrolysis pathways of propane and n-butane, which are the main components of liquefied petroleum gas （LPG）, for better understanding the pyrolysis behavior of LPG in hydrogen thermal plasma. Over 60 possible reactions are considered. The reaction enthalpies and activation energies of these reactions are calculated and analyzed with a Gaussian method of B3LYP and basic set of 6-31G （d,p）. A most possible reaction pathway is brought up. According to this reaction pathway, the main products of LPG pyrolysis are acetylene, ethylene, methane, ethane and extra hydrogen. Acetylene mainly comes from the pyrolysis of propylene and ethylene, and hydrogen abstraction reactions are the main source of extra hydrogen gas. Active H. radicals are found to play a very important role in many reactions, and they can remarkably lower the energies needed for reactions.

Heterostructuring 2D Co_(2)P nanosheets with 0D CoP via a saltassisted strategy for boosting hydrogen evolution from ammonia borane hydrolysis

Ammonia borane(NH3BH3,AB)holds promise for chemical storage of hydrogen.However,designing superb and low-cost photocatalyst to drive hydrogen evolution from AB under visible light irradiation is highly desirable but remains a major challenge for promoting the practical utilization of AB.Herein,we demonstrated a heterostructure photocatalyst consisting of zerodimensional(0D)CoP nanoparticles immobilized on two-dimensional(2D)Co_(2)P nanosheets(CoP/Co_(2)Ps)as a high-performance and low-cost catalyst for hydrogen evolution from AB hydrolysis,in which 0D/2D heterostructure was synthesized using the saltinduced phase transformation strategy.Interestingly,the optimized CoP/Co_(2)Ps exhibit a robust H_(2) evolution rate of 32.1 L∙min^(−1)∙g_(Co)^(−1),corresponding to a turnover frequency(TOF)value of 64.1 min^(−1),being among the highest TOF for non-noblemetal catalysts ever reported,even outperforming some precious metal catalysts.This work not only opens a new avenue to accelerate hydrogen evolution from AB by regulating the electronic structures of heterointerfaces,but also provides a novel strategy for the construction of precious-metal-free materials for hydrogen-related energy catalysis in the future.

混合丁烯氧化脱氢双层床催化剂体系的协同作用机理(英文)

目的:通过对混合丁烯氧化脱氢过程进行反应表征,对由Zn Fe_2O_4和Co_9Bi_1Fe_3Mo_(12)O_(51)组成的双床层催化剂体系中存在的协同机理进行解释;将异构化反应过程纳入反应体系,得出混合丁烯转化率和丁二烯收率上升的原因。创新点:1.提出基于丁烯异构体在床层之间浓度重分布和异构化效应抑制作用的协同作用机理;2.设计验证实验,从直观角度证实机理,并优化了催化剂的装填量和装填顺序。方法:1.通过单一丁烯和混合丁烯的氧化脱氢反应,对单一催化剂和双床层催化剂进行反应评估,得到相关反应数据;2.通过设计对比实验,从改变参加反应物质的直观角度对协同机理进行验证和解释;3.对参加反应的双层床催化剂中两种催化剂的装填量和装填顺序进行优化,为进一步研究组合型催化剂提供实验基础。结论:1.Zn Fe_2O_4对两种2-丁烯有更优的催化效果,而Co_9Bi_1Fe_3Mo_(12)O_(51)对1-丁烯有更优的催化效果,由两者组成的双层床催化体系对单一丁烯和混合丁烯的反应效果都有所提升,证明两种催化剂之间存在协同效应。2.双层床催化剂体系中,两种催化剂之间的协同作用机理是:催化剂不同活性导致丁烯异构体在床层之间的浓度发生重分布,同时由于多种异构体同时存在抑制了异构化反应。3.对双层床催化剂体系的装填顺序和装填量的优化结果表明,Zn Fe_2O_4装填在上层,Co_9Bi_1Fe_3Mo_(12)O_(51)装填在下层,且两者比例处于4:6到6:4之间时催化效果最佳。