Fine-tuning electronic structure of N-doped graphitic carbon-supported Co-and Fe-incorporated Mo_(2)C to achieve ultrahigh electrochemical water oxidation activity

Mo_(2)C is an excellent electrocatalyst for hydrogen evolution reaction(HER).However,Mo_(2)C is a poor electrocatalyst for oxygen evolution reaction(OER).Herein,two different elements,namely Co and Fe,are incorporated in Mo_(2)C that,therefore,has a finely tuned electronic structure,which is not achievable by incorporation of any one of the metals.Consequently,the resulting electrocatalyst Co_(0.8)Fe_(0.2)-Mo_(2)C-80 displayed excellent OER catalytic performance,which is evidenced by a low overpotential of 214.0(and 246.5)mV to attain a current density of 10(and 50)mA cm^(-2),an ultralow Tafel slope of 38.4 mV dec^(-1),and longterm stability in alkaline medium.Theoretical data demonstrates that Co_(0.8)Fe_(0.2)-Mo_(2)C-80 requires the lowest overpotential(1.00 V)for OER and Co centers to be the active sites.The ultrahigh catalytic performance of the electrocatalyst is attributed to the excellent intrinsic catalytic activity due to high Brunauer-Emmett-Teller specific surface area,large electrochemically active surface area,small Tafel slope,and low chargetransfer resistance.

Upcycling plastic wastes into value-added products via electrocatalysis and photoelectrocatalysis

Plastic,renowned for its versatility,durability,and cost-effectiveness,is indispensable in modern society.Nevertheless,the annual production of nearly 400 million tons of plastic,coupled with a recycling rate of only 9%,has led to a monumental environmental crisis.Plastic recycling has emerged as a vital response to this crisis,offering sustainable solutions to mitigate its environmental impact.Among these recycling efforts,plastic upcycling has garnered attention,which elevates discarded plastics into higher-value products.Here,electrocatalytic and photoelectrocatalytic treatments stand at the forefront of advanced plastic upcycling.Electrocatalytic or photoelectrocatalytic treatments involve chemical reactions that facilitate electron transfer through the electrode/electrolyte interface,driven by electrical or solar energy,respectively.These methods enable precise control of chemical reactions,harnessing potential,current density,or light to yield valuable chemical products.This review explores recent progress in plastic upcycling through electrocatalytic and photoelectrocatalytic pathways,offering promising solutions to the plastic waste crisis and advancing sustainability in the plastics industry.

Direct photoelectrochemical nitrate synthesis in an acidic electrolyte from N_(2)by a hole coupled oxygen atom transfer process

Ammonia is an important chemical for pharmaceutical,agriculture,industry,as well as energy production et al.However,the industrial production of ammonia using the Haber-Bosch process is energy-intensive,which stimulates us to explore a cost-effective and low-carbon footprint way for the synthesis of ammonia[1–3].Electrochemical(EC)synthesis of ammonia from an aqueous N_(2)reduction reaction(NRR)has gained significant attention in recent years,while the high dissociation energy of the N≡N bond(941 kJ/mol),as well as higher over-potential than hydrogen evolution reaction(HER),cause a lower efficiency[4].

Artificial photosynthesis for high-value-added chemicals:Old material,new opportunity

Solar energy utilization has drawn attention due to ever-increasing environmental and energy issues.Photoelectrochemical(PEC)and photocatalytic(PC)water splitting for hydrogen production,which is the most popular and well-established solar-to-chemical conversion process,has been studied thoroughly to date but is now facing limitations related to low conversion efficiency.To resolve this issue,research in PEC cells or photocatalysts has recently aimed to produce alternative value-added chemicals by modifying their redox reactions,which potentially enables high economic reward to compensate for the low efficiency.Here,various kinds of redox reactions that decouple classic water splitting reactions to produce value-added chemicals via PEC and PC processes are introduced.Successful coupling of CO_(2) reduction,O_(2) reduction and organic synthesis with either water oxidation or water reduction is comprehensively discussed from the perspective of basic fundamental and product selectivity in terms of the band structure of materials,cocatalyst design,and thermodynamics and kinetics of the reactions.Throughout the review,future challenges and opportunities are suggested with respect to the redesigned artificial synthesis,which might be an alternative development for the commercialization of PEC or PC value-added chemical production technologies in the near future.

Black TiO2: What are exact functions of disorder layer

Among the substantial amount of photocatalyst materials,TiO2 has been enthusiastically studied for a few decades due to its outstanding photocatalytic activity and stability.Recently,black TiO2 consisting of approximately 2 nm of thin disorder layer around the surface showed surprisingly high solar hydrogen generation ability.The disorder layer of TiO2 can enhance its light absorption,charge separation,and surface reaction abilities,however exact fundamentals of photocatalytic water-splitting pathways are still ambiguous.Herein,recent progress and investigations on exact functions of disorder layer and its application in photocatalytic CO2 reduction will be discussed.Throughout the comprehensive studies on disorder layer of TiO2,disorder engineering on photocatalyst materials will suggest the further extension of developing solarfuel production technologies.

Electrochemical partial reduction of Ni(OH)_(2) to Ni(OH)_(2)/Ni via coupled oxidation of an interfacing NiAl intermetallic compound for robust hydrogen evolution

Ni-based porous electrocatalysts have been widely used in the hydrogen evolution reaction(HER)in alkaline water electrolysis,and the catalysts are produced by selective leaching of Al from Ni-Al alloys.It is well known that chemical leaching of Ni-Al intermetallic compound(IMC)generates a high surface area in Ni(OH)_(2).However,the Ni(OH)_(2) produced by leaching the Ni-Al intermetallic compound retards the hydrogen evolution reaction,which is attributed to its weak hydrogen adsorption energy.In this study,we controlled the chemical state of Ni using plasma vapor deposition(PVD)followed by heat treatment,selective Al leaching,and electrochemical reduction.X-ray diffraction(XRD),scanning microscopy(SEM),transmission electron microscopy(TEM),and energy-dispersive X-ray spectroscopy(EDS)were used to confirm the phase evolution of the electrocatalysts during fabrication.We reveal that the heat-treated Ni-Al alloy with a thick Ni2Al3surface layer underwent selective Al leaching and produced biphasic interfaces comprising Ni(OH)_(2) and NiAl IMCs at the edges of the grains in the outermost surface layer.Coupled oxidation of the interfacing NiAl IMCs facilitated the partial reduction of Ni(OH)_(2) to Ni(OH)_(2)/Ni in the grains during electrochemical reduction,as confirmed by X-ray photoelectron spectroscopy(XPS).An electrocatalyst containing partially reduced Ni(OH)_(2)/Ni exhibited an overpotential of 54 mV at 10 mA/cm^(2) in a half-cell measurement,and a cell voltage of 1.675 V at 0.4 A/cm2for single-cell operation.A combined experimental and theoretical study(density functional theory calculations)revealed that the superior HER activity was attributed to the presence of partially reduced metallic Ni with various defects and residual Al,which facilitated water adsorption,dissociation,and finally hydrogen evolution.

Carbon energy: A multidisciplinary exploration of energy technologies and carbon materials science

Today’s world is stressed by the ever-increasing demand for energy and the disastrous climate changes.New technologies that generate,convert,and store energy in a greener and more efficient way become increasingly critical in building a sustainable society.On this front,batteries,capacitors,fuel cells,and solar cells play the indispensable roles as the powers for applications,for example,electric vehicles shall mitigate our reliance on the depleting fossil fuels.It is crucial to invent new materials or technologies to improve the electrochemical performance of energy storage/conversion devices with higher energy,better power,longer cycle life,and better safety.One of the most important areas pertains to carbon-based materials.Researchers from different fields design carbon-based materials for low-cost energy devices with great portability and functionality.

Solar-harvesting lead halide perovskite for artificial photosynthesis

Facing the upcoming energy and environmental crisis, artificial photosynthesis for producing various solar fuels (e.g., hydrogen or carbon products) via a solar-to-chemical energy conversion is receiving increasing attention;however, its low conversion efficiency is a challenge for commercialization. To resolve low-efficiency issues, lead halide perovskite (LHP) with outstanding optoelectronic properties compared to conventional semiconductors can be a promising approach to improve the solar-to-fuel conversion reactions and solar fuel production efficiency. The tunable energy band structure and charge transport properties of LHP have promoted their extensive use in the production of solar fuels. This study summarizes the recent advancements of LHP-mediated solar-to-fuel conversions, classified by their redox reactions, namely solar water splitting, hydrohalic acid splitting, and CO_(2) reduction. Advanced approaches for achieving high conversion efficiency and long-term durability are discussed, including the configuration of devices, the composition of LHP, and the protection strategy of LHP. Moreover, the reaction mechanisms of LHP-mediated solar-to-chemical energy conversions and obstacles for enhancing the conversion efficiency are discussed. Finally, we present the perspectives on the development of LHP-incorporated solar-to-fuel conversion systems, which might open a new era of energy harvesting and storage.

光催化CO_(2)还原多原子催化剂的设计与制备进展

光催化CO_(2)还原合成太阳能燃料对缓解CO_(2)排放引起的全球变暖和降低化石燃料消耗具有重要意义.然而,目前的光催化剂仍然存在反应动力学缓慢和选择性不理想的问题,特别是对于C_(2+)产物的生成,极大地限制了光催化的工业化进程.过去几十年中,关于太阳能驱动的CO_(2)还原的研究展示出鼓舞人心的结果,包括活性位点的构建.本综述重点介绍了通过构建活性位点制备原子级分散催化剂在光催化CO_(2)还原中的最新进展,包括两个独立的活性位点、成对双活性位点和基于活性位点构型的纳米团簇.此外,详细讨论了CO_(2)在活性位点上的活化机制和表征方法.特别是考虑到实验研究与实际应用之间的差距,整合实验和理论的结果,以实现潜在的结构-活性关系和高目标产物选择性发展.最后,概述了该领域存在的挑战,并展望了活性位点的合理设计和机理研究.

Precise control of surface oxygen vacancies in ZnO nanoparticles for extremely high acetone sensing response

ZnO has been studied intensely for chemical sensors due to its high sensitivity and fast response.Here,we present a simple approach to precisely control oxygen vacancy contents to provide significantly enhanced acetone sensing performance of commercial ZnO nanopowders.A combination of H_(2)O_(2)treatment and thermal annealing produces optimal surface defects with oxygen vacancies on the ZnO nanoparticles(NPs).The highest response of~27,562 was achieved for 10 ppm acetone in 0.125 MH_(2)O_(2)treated/annealed ZnO NPs at the optimal working temperature of 400℃,which is significantly higher than that of reported so far in various acetone sensors based on metal oxide semiconductors(MOSs).Furthermore,first-principles calculations indicate that pre-adsorbed O formed on the surface of H_(2)O_(2)treated ZnO NPs can provide favorable adsorption energy,especially for acetone detection,due to strong bidentate bonding between carbonyl C atom of acetone molecules and pre-adsorbed O on the ZnO surface.Our study demonstrates that controlling surface oxygen vacancies by H_(2)O_(2)treatment and re-annealing at optimal temperature is an effective method to improve the sensing properties of commercial MOS materials.

Quasi-homogeneous photoelectrochemical organic transformations for tunable products and 100%conversion ratio

Photoelectrochemical(PEC)organic transformation at the anode coupled with cathodic H_(2) generation is a potentially rewarding strategy for efficient solar energy utilization.Nevertheless,achieving the full conversion of organic substrates with exceptional product selectivity remains a formidable hurdle in the context of heterogeneous catalysis at the solid/liquid interface.Here,we put forward a quasi-homogeneous catalysis concept by using the reactive oxygen species(ROS),such as·OH,H_(2)O_(2) and SO_(4)^(2-),as a charge transfer mediator instead of direct heterogeneous catalysis at the solid/liquid interface.In the context of glycerol oxidation,all ROS exhibited a preference forfirst-order reaction kinetics.These ROS,however,showcased distinct oxidation mechanisms,offering a range of advantages such as100%conversion ratios and theflexibility to tune the resulting products.Glycerol oxidative formic acid with Faradaic efficiency(FE)of 81.2%was realized by the H_(2)O_(2) and·OH,while SO_(4)^(2-)was preferably for glycerol conversion to C3 products like glyceraldehyde and dihydroxyacetone with a total FE of about 80%.Strikingly,the oxidative coupling of methane to ethanol was successfully achieved in our quasi-homogeneous system,yielding a remarkable production rate of 12.27 lmol h^(-1) and an impressive selectivity of 92.7%.This study is anticipated to pave the way for novel approaches in steering solar-driven organic conversions by manipulating ROS to attain desired products and conversion ratios.