Copper foam-derived electrodes as efficient electrocatalysts for conventional and hybrid water electrolysis

Electrochemical water splitting has been demonstrated as a promising technology for the renewable generation of green hydrogen from water.Despite the extensive progress in materials science,one particular challenge for further development towards industrial application lies in the rational design and exploitation of efficient and cost-effective materials,especially oxygen evolution reaction(OER)electrocatalysts at the anode.In addition,attempts to replace the OER with other more oxidizable anode reactions are being evaluated as a groundbreaking strategy for generating hydrogen at lower potentials and reducing overall energy costs while producing valuable chemicals simultaneously.Compared with Fe/Co/Ni-based compounds,Cu-based materials have not received extensive research attention for electrode designs despite their high conductivity and abundant earth reserves.In this review,combining with the advantages of a three-dimensional network structure of metal foams,we summarize recent progress on Cu foam(CF)-derived materials as efficient electrocatalysts towards pure water electrolysis and hybrid water electrolysis.The advantages of CF and design strategies to enhance the electrocatalytic activity and operational durability are presented first.Catalyst design and fabrication strategies are then highlighted and the structure-activity relationship is also discussed.Finally,we propose challenges and perspectives on self-supported electrodes beyond CF-derived materials.

Decoupled water electrolysis:Flexible strategy for pure hydrogen production with small voltage inputs

Hydrogen gas is widely regarded as an ideal green energy carrier and a potential alternative to fossil fuels for coping with the aggravating energy crisis and environmental pollution.Currently,the vast majority of the world's hydrogen is produced by reforming fossil fuels;however,this hydrogen-making technology is not sustainable or environmentally friendly because ofits high energy consumption and large carbon emissions.Renewables-driven water splitting(2H_(2)0-2H_(2)+0_(2))becomes an extensively studied scheme for sustain-able hydrogen production.Conventional water electrolysis requires an input voltage higher than 1.23 V and forms a gas mixture of H_(2)/O_(2),which results in high electricity consumption,potential safety hazards,and harmful reactive oxygen species.By virtue of the auxiliary redox mediators(RMs)as the robust H^(+)/e^(-)reservoir,decoupled electrolysis splits water at a much lower potential and evolves O_(2)(H_(2)O+RMS_(ox)-O_(2)+H-RMS_(red))and H_(2)(H-RMS_(red)-H_(2)+RMS_(ox))at separate times,rates,and spaces,thus pro-ducing the puretarget hydrogen gas safely.Decoupled electrolysis has accelerated the development ofwater electrolysis technology for H_(2) production.However,itis still lack of a comprehensive and in-depth review in this field based on different types of RMs.This review highlights the basic principles and critical progress of this emerging water electrolysis mode over the past decade.Several representative examples are then dis-played in detail according to the differences in the RMs.The rational choice and design of RMs have also been emphasized.Subsequently,novel applications of decoupled water splitting are briefly discussed,including the manufacture of valuable chemicals,Cl_(2) production,pollutant degradation,and other half-reactions in artificial photosynthesis.Finally,thekey characteristics and disadvantages of each type of mediator are sum-marized in depth.In addition,we present an outlook for future directions in decoupled water splitting.Thus,the flexibility in the design of mediators provides huge space for improving this electrochemical technology.@2024 Science Press and Dalian Institute of Chemical Physics,Chinese Academy of Sciences.Published by ELSEVIER B.V.and Science Press.All rights reserved.

Efficiency of locally available filter media on fluoride and phosphate removal for household water treatment system

Since conventional water treatment is not affordable in developing countries,looking for locally available and alternative treatment options is mandatory.Removal of fluoride and phosphate can be achieved by designing appropriate filtration media from different materials such as sand,calcined clay,pumice,scoria and bone char.This study was designed to determine the removal efficiency of these locally available filter media with respect to detention time and pH.The filtration apparatuses(tank) were filled separately with stone,gravel with grain size 0.6-4.75 mm and 40 cm deep,sand(ES = 0.15—0.35 mm and UC = 1.5-3),calcined clay,pumice,scoria and bone char with grain size 0.25-0.5 inch.Water samples were prepared using glass bottles with fluoride concentrations of 6 and 8 mg/1 and phosphate concentration of 4 mg/1.Laboratory analysis was carried out before and after filtration to determine the removal efficiency of each medium.It was found that the highest removal of fluoride was achieved by bone char(89.65%),followed by pumice(82.4%).However,bone char has rather increased the concentration of phosphate by 63.8%.Sand was the most efficient media to remove phosphate,managing to remove by 70%.Therefore,it is an attractive option to use these locally available,environmental friendly and appropriate technologies for efficient removal of both fluorine and phosphate at the household or community water treatment level.

Evaluation of Environmental Impact Assessment Factors in Maritime Industry

The environmental impact of shipping sector includes the pollution caused by vessels to air and water environment.The water pollution is primarily caused by ship accidents and by untreated ballast water.To avoid maritime accidents,a complex system of regulations and safety management measures has been initiated to minimize and possibly avoid similar maritime disasters in the future.On the other hand,untreated ballast water,despite the ease of management by shipping companies,is regarded as one of the major maritime threats internationally and arguably a severe threat to biodiversity.The International Convention on the Control and Management of Ballast of Ships and Sediments,entered into force in September 2017,focusing on the prevention of the risk of importation and the proliferation of foreign species after the discharge of untreated ballast water from vessels.An option to reduce this risk is to install water treatment systems on the ballast tanks.Air pollution deriving from vessels is an additional issue that has great significance and impact on public health and the environment in general.Ships emit large amounts of air pollutants,mainly in the form of SO_(x)(Sulfur O_(x)ide),NO_(x)(Nitrogen O_(x)ide)and particulate matter,which are constantly growing and affecting humans.Vessels also produce nearly 3%of the world’s total greenhouse gas emissions,leading to rampant weather conditions.From 1 January 2020,the IMO(International Maritime Organization)imposed a new global sulfur emission ceiling of 0.5%on fuels,a reduction from the current limit of 3.5%,aiming at a gradual extinction of sulfur emissions in the near future.Pursuant to the previous analysis,three systems/indicators that are applied to vessels are going to be assessed,based on UNCTAD(United Nations Conference on Trade and Development)Report Data,to evaluate their impact in correlation to the measure of compliance to the relevant regulations so far:(i)the ship must have an equipped and installed ballast treatment system;(ii)the ship must be equipped and fitted with a special filter to eliminate sulfur emissions;(iii)the ship must comply with Tier III regulations to successfully reduce NO_(x)emissions.

Dyeing PET Textile with C.I.Disperse Red 60 and C.I. Disperse Orange 25 in Supercritical CO_2

For a better understanding of the feasibility of supercritieal fluid dyeing （SFD） and more available information for the process development, the experiments of dyeing PET textile with C.I. disperse red 60 （anthraquinone type） and C. I. disperse orange 25 （azo type） in supercritieal CO2 were carried out with a high-pressure dyeing apparatus at temperatures from 80 to 130℃ and pressure up to 31 MPa. The effect of operating conditions on color yield （K/S） was investigated in SFD experiment, and the optimum operating conditions for the above two disperse dyes were obtained as follows： the temperature 120℃, the pressure 25 MPa and the dyeing time 100 min. As compared with SFD, the conventional water dyeing （CWD） was carried out with the same dyes and textile. The results show that the better fastness, levelness and apparent color can be achieved in SFD and the SFD process has many significant advantages over the CWD process.