镍基金属有机框架衍生的双功能电催化剂用于析氢和析氧反应

开发高活性、低成本的析氢反应和析氧反应电催化剂对于能源的可持续发展至关重要。金属有机框架衍生的纳米材料已经成为一类非常有前景的非贵金属双功能电催化剂,但是目前对镍基金属有机框架衍生的双功能电催化剂的深入研究并不全面,其催化活性和稳定性还有待进一步提高。本文制备了一种棒状多孔碳负载镍纳米颗粒的新型电催化剂,并将其用作电催化析氢和析氧反应。实验研究结果表明该类电催化剂表现出优异的析氢和析氧反应活性和长期稳定性,在10 mA·cm^(-2)的电流密度下,析氢反应和析氧反应的过电位分别为120和350 mV。我们认为:材料可控的纳米结构和均匀分布的活性位点共同提升了复合材料的电催化性能。

Selective hydrogenation of 1,3-butadiene on iridium nanostructures:Structure sensitivity, host effect, and deactivation mechanism

A systematic study on the structure sensitivity,host effect,and the deactivation mechanism of Ircatalyzed selective hydrogenation of 1,3-butadiene,a key process in the purification of alkadiene for the upgrading of C4 cut,is presented by coupling steady-state catalytic testing,in-depth characterization,kinetic evaluation,and density functional theory calculations.We reveal that:(i) 1,3-Butadiene hydrogenation on iridium is structure-sensitive with the optimal particle size of about 2 nm,and the H_(2) dissociation energy is a reliable activity descriptor;(ii) The nature of the NC hosts exerts a critical impact on the catalytic performance,and balanced nitrogen content and speciation seem key for the optimized performance;and (iii) Different deactivation mechanisms occur:fouling by coke deposition on the catalysts with a high N:C ratio (>1),and site blockage due to the competitive adsorption between 1-butene/cis-2-butene and 1,3-butadiene.These molecular insights provide valuable guidelines for the catalyst design in selective hydrogenations.

An arch-shape wood evaporator decorated by metal-organic framework for solar interface evaporation

To achieve sustainable desalination and water purification,solar interface evaporation technology is an effective means due to its high energy efficiency.Reasonable photothermal conversion materials and surface design are crucial for the interfacial solar evaporation process.How to design water transport routes and thermal insulating layers simultaneously is one of the major challenges to solar interface evaporation technology today.Herein,this work reports an arch-shaped wood evaporator(pine@carbon black(CB)-metal-organic framework-801(MOF-801)-36%)for efficient,fast and continuous interfacial solar evaporation,which is composed of an arch-shaped wood substrate,MOF-801,and CB as a light absorption layer.The archshaped structure has a double-sided evaporation effect,which has a synergistic effect on augmenting solar evaporation efficiency.In addition,the in-situ growth of MOF-801 in pretreated wood microchannels renders the wood evaporator a significant function of reducing the equivalent enthalpy of evaporation due to the reduction of the hydrogen bonding density of water molecules as they pass through the wood channels.The best evaporation rate of the arch-shaped wood evaporator can reach 2.535 kg·m^(−2)·h^(−1),and the efficiency reaches 93.7%under the irradiation of 1 sun illumination.Notably,it could be used for desalination and wastewater treatment to collect fresh water that meets drinking requirements set by the World Health Organization(WHO).This integrated evaporator provides an efficient way for commercial portable photothermal conversion and new ideas for advanced solar-driven water treatment technology.

Carbon Nitride with Single-Atom Nickel as Co-Catalyst for Visible-Light Promoted C—O Coupling

Solar-driven cross-coupling reactions by dual nickel/photocatalysis under mild conditions have received considerable attention.However,the existing photo/nickel dual catalytic cross-coupling reactions require the addition of expensive photosensitizers and organic ligands,and the catalytic activity is inadequate.Herein,we report a nickel single-atom heterogeneous catalyst supported on mesoporous carbon nitride for photocatalytic C—O coupling reaction between 4-bromobenzonitrile and ethanol,affording 4-ethoxybenzonitrile in excellent yield compared to a semi-heterogeneous catalytic system.The catalytic system exhibits a broad substrate scope including ketones,aldehydes,esters,and amides.This work presents a simple and cost-effective strategy for anchoring metal single atoms onto carbon nitride,providing a new platform for enabling high-performance photocatalytic production of aryl ether compounds.

Anchoring Co3O4 nanoparticles on MXene for efficient electrocatalytic oxygen evolution

Rational design and controllable synthesis of efficient electrocatalysts for water oxidation is of significant importance for the development of promising energy conversion systems, in particular integrated photoelectrochemical water splitting devices. Cobalt oxide(Co3O4) nanostructures with mixed valences(Ⅱ,Ⅲ)have been regarded as promising electrocatalysts for the oxygen evolution reaction(OER). They are able to promote catalytic support of OER but with only modest activity. Here, we demonstrate that the OER performance of cubic Co3O4 electrocatalyst is obviously improved when they are anchored on delaminated two-dimensional(2D) Ti3C2 MXene nanosheets. Upon activation the overpotential of the hybrid catalyst delivers 300 m V at a current density of 10 m A cm(2) in basic solutions, which is remarkably lower than those of Ti3C2 MXene and Co3O4 nanocubes. The strong interfacial electrostatic interactions between two components contribute to the exceptional catalytic performance and stability. The enhanced OER activity and facile synthesis make these Co3O4 nanocubes-decorated ultrathin 2D Ti3C2 MXene nanosheets useful for constructing efficient and stable electrodes for high-performance electrochemical water splitting.

Synthesis of atomic platinum with high loading on metal-organic sulfide

Synthesis of ultrafine noble metal with sizes down to nanoscale and even atomic scale is of great significance for heterogeneous catalysis. However, the metal loading is usually kept below 2 wt% due to the aggregation tendency at higher metal contents. Herein, by mimicking the multicentered metal sulfur cluster of metalloenzyme, a bioinspired synthesis of isolated noble metal atoms on the metal-organic sulfide(MOS) framework was reported. The sulfur-rich framework featuring [Mo_(3)S_(2)Br_(6)]^(2-) cluster as the building block and dithiol as the linking node was constructed via chemical bonding and employed to support atomic metal species. Remarkably, highly dispersed platinum atoms with a loading amount as high as 18.5 wt% on the underlying sulfurrich framework could be obtained after reduction. By increasing the number of benzene rings in the dithiol, the pore size and even the wettability of the MOS frameworks could be modulated. The general applicability of the synthesis could also be extended to the synthesis of atomic Pd. Furthermore,the Pt-loaded MOS could serve as the catalyst for selective hydrogenation of phenylacetylene to styrene in both organic solvent and pure water. Density function theory calculation demonstrated that the atomic Pt sites in the sulfur-rich coordination environment could activate H_(2) molecules and chemoselectively catalyze the semi-hydrogenation of phenylacetylene to styrene through moderately low energy barriers.The metalation of such a versatile MOS framework will shed light on the synthesis of bioinspired catalytic materials with well-defined structures for more diverse applications.

Amino acid promoted hydrogen battery system using Mn-pincer complex for reversible CO_(2) hydrogenation to formic acid

The worldwide energy system developed in the past century is highly dependent on non-renewable fossil feedstocks.Hence,the concentration of carbon dioxide(CO_(2))in the atmosphere has continuously increased from 280 ppm(parts per million)to>420 ppm since the industrial revolution[1–5].This excessive emission of CO_(2) causes global warming and ocean acidification.In this context,the Paris Agreement on Climate Change adopted in 2015 recognized the necessity of holding the increase of global average temperature below 2℃,preferably 1.5℃,above pre-industrial levels,and reaching a CO_(2)-neutral process by 2050.