Hierarchical Interconnected NiMoN with Large Specific Surface Area and High Mechanical Strength for Efficient and Stable Alkaline Water/Seawater Hydrogen Evolution

NiMo-based nanostructures are among the most active hydrogen evolution reaction(HER)catalysts under an alkaline environment due to their strong water dissociation ability.However,these nanostructures are vulnerable to the destructive effects of H_(2) production,especially at industry-standard current densities.Therefore,developing a strategy to improve their mechanical strength while maintaining or even further increasing the activity of these nanocatalysts is of great interest to both the research and industrial communities.Here,a hierarchical interconnected NiMoN(HW-NiMoN-2h)with a nanorod-nanowire morphology was synthesized based on a rational combination of hydrothermal and water bath processes.HW-NiMoN-2h is found to exhibit excellent HER activity due to the accomodation of abundant active sites on its hierarchical morphology,in which nanowires con-nect free-standing nanorods,concurrently strengthening its structural stability to withstand H_(2) production at 1 A cm^(−2).Seawater is an attractive feedstock for water electrolysis since H_(2) generation and water desalination can be addressed simultaneously in a single process.The HER performance of HW-NiMoN-2h in alkaline seawater suggests that the presence of Na+ions interferes with the reation kinetics,thus lowering its activity slightly.However,benefiting from its hierarchical and interconnected characteristics,HW-NiMoN-2h is found to deliver outstanding HER activity of 1 A cm^(−2) at 130 mV overpotential and to exhibit excellent stability at 1 A cm^(−2) over 70 h in 1 M KOH seawater.

Market-based solution in China to finance the clean from the dirty

Financial incentives play a key role in promoting renewable energy investments that can help China achieve the‘dual carbon’goal.The national emissions trading scheme(ETS)and the renewable energy portfolio standard(RPS)are two existing market-based policy instruments that can generate stable expected returns for low-carbon projects.This paper studies the interactive distribution effects of these two market-based instruments.We use the micro-level thermal power plant data to investigate the abatement effects of the national ETS,in which the details show that the existing rate-based ETS will result in higher negative impacts on power units,whose installed capacities are smaller than 400 MW.The interactive distribution effects between the two markets will occur when the permit allocation standards of the national ETS become stricter than the existing ones.Provinces in Eastern China and Northern China will face high pressure on costs in both ETS and RPS markets.When the levels of the permit allocation standards are set as 70%of the existing ones and the carbon price is assumed to be 200 yuan/ton in 2030,the annual market size of the national ETS will be nearly 100 billion yuan,and the annual market size is predicted to be 250 billion yuan.In the existing rate-based national ETS,the China Certified Emission Reduction(CCER)mechanism will have an offsetting effect,which should be taken into serious consideration during the policy-making processes in the future.

Recent Advances in Self-Supported Layered Double Hydroxides for Oxygen Evolution Reaction

Electrochemical water splitting driven by clean and sustainable energy sources to produce hydrogen is an efficient and environmentally friendly energy conversion technology.Water splitting involves hydrogen evolution reaction(HER)and oxygen evolution reaction(OER),in which OER is the limiting factor and has attracted extensive research interest in the past few years.Conventional noble-metal-based OER electrocatalysts like IrO_(2) and RuO_(2) suffer from the limitations of high cost and scarce availability.Developing innovative alternative nonnoble metal electrocatalysts with high catalytic activity and long-term durability to boost the OER process remains a significant challenge.Among all of the candidates for OER catalysis,selfsupported layered double hydroxides(LDHs)have emerged as one of the most promising types of electrocatalysts due to their unique layered structures and high electrocatalytic activity.In this review,we summarize the recent progress on self-supported LDHs and highlight their electrochemical catalytic performance.Specifically,synthesis methods,structural and compositional parameters,and influential factors for optimizing OER performance are discussed in detail.Finally,the remaining challenges facing the development of self-supported LDHs are discussed and perspectives on their potential for use in industrial hydrogen production through water splitting are provided to suggest future research directions.

Optimization of the fused deposition modeling-based fabrication process for polylactic acid microneedles

A microneedle(MN)array is a novel biomedical device adopted in medical applications to pierce through the stratum corneum while targeting the viable epidermis and dermis layers of the skin.Owing to their micron-scale dimensions,MNs can minimize stimulations of the sensory nerve fibers in the dermis layer.For medical applications,such as wound healing,biosensing,and drug delivery,the structure of MNs significantly influences their mechanical properties.Among the various microfabrication methods for MNs,fused deposition modeling(FDM),a commercial 3D printing method,shows potential in terms of the biocompatibility of the printed material(polylactic acid(PLA))and preprogrammable arbitrary shapes.Owing to the current limitations of FDM printer resolution,conventional micron-scale MN structures cannot be fabricated without a post-fabrication process.Hydrolysis in an alkaline solution is a feasible approach for reducing the size of PLA needles printed via FDM.Moreover,weak bonding between PLA layers during additive manufacturing triggers the detachment of PLA needles before etching to the expected sizes.Furthermore,various parameters for the fabrication of PLA MNs with FDM have yet to be sufficiently optimized.In this study,the thermal parameters of the FDM printing process,including the nozzle and printing stage temperatures,were investigated to bolster the interfacial bonding between PLA layers.Reinforced bonding was demonstrated to address the detachment challenges faced by PLA MNs during the chemical etching process.Furthermore,chemical etching parameters,including the etchant concentration,environmental temperature,and stirring speed of the etchant,were studied to determine the optimal etching ratio.To develop a universal methodology for the batch fabrication of biodegradable MNs,this study is expected to optimize the conditions of the FDM-based fabrication process.Additive manufacturing was employed to produce MNs with preprogrammed structures.Inclined MNs were successfully fabricated by FDM printing with chemical etching.This geometrical structure can be adopted to enhance adhesion to the skin layer.Our study provides a useful method for fabricating MN structures for various biomedical applications.