2024 Vol. 9, No. 7

Cover info & Content
Short communication
Abstract:
Plasmon-induced hot-electron transfer from metal nanostructures is being intensely pursed in current photocatalytic research, however it remains elusive whether molecular-like metal clusters with excitonic behavior can be used as light-harvesting materials in solar energy utilization such as photocatalytic methanol steam reforming. In this work, we report an atomically precise Cu13 cluster protected by dual ligands of thiolate and phosphine that can be viewed as the assembly of one top Cu atom and three Cu4 tetrahedra. The Cu13H10(SR)3(PR’3)7 (SR = 2,4-dichlorobenzenethiol, PR’3 = P(4-FC6H4)3) cluster can give rise to highly efficient light-driven activity for methanol steam reforming toward H2 production.
Review article
Abstract:
While carbon dioxide (CO2) is a major greenhouse gas, it is also an important C1 resource. In the trend of energy conservation and emission reduction, electrocatalytic reduction has become a very promising strategy for CO2 utilization because it can convert CO2 directly to high-valued chemicals and fuels under mild conditions. In particular, the product CO and by-product H2 can be combined into syngas by an electrocatalytic CO2 reduction reaction (CO2RR) in an aqueous medium. Different molar ratios of CO and H2 may be used to produce essential bulk chemicals or liquid fuels such as methanol, alkanes, and olefins through thermochemical catalysis, Fischer–Tropsch synthesis, microbial fermentation, and other techniques. This work discusses the latest strategies in controlling the molar ratio of CO/H2 and improving the yield of CO2RR-to-syngas. The challenges of electrocatalytic syngas production are analyzed from an industrial application perspective, and the possible measures to overcome them are proposed in terms of new catalyst design, electrolyte innovation, flow reactor optimization, anodic reaction coupling, and operando technique application.
Research papers
Abstract:
The conversion of biomass into sugar platform compounds is very important for the biorefinery industry. Pretreatment is essential to the biomass of the sugar platform, however, the lignin obtained by pretreatment, as a key part of lignocellulose, generally has a passive effect on the enzymatic hydrolysis of cellulose into sugars. In this study, p-TsOH (p-toluenesulfonic acid), DES (Deep eutectic solvent) and CAOSA (cooking with active oxygen and solid alkali) pretreatment ways were used to fraction lignin from bamboo biomass. After CAOSA treatment, the hydrolysis efficiency of the pulp was 95.57%. Moreover, the effect of different treatment methods on lignin properties was studied and the promotion effect of lignin was investigated by adding it to the cellulose enzymatic hydrolysis system. In this work, the results showed that CAOSA-extracted lignin with lower Đ (1.31–1.25) had a better adsorption effect on the enzyme protein. p-TsOH-extracted lignin with a larger S/G ratio enhanced the inhibition of enzymatic hydrolysis. In addition, the presence of -COOHs in lignin could reduce its inhibitory effect on cellulose saccharification.
Abstract:
Photoelectrochemical NO3- reduction (PEC NITRR) not only provides a promising solution for promoting the global nitrogen cycle, but also converts NO3- to the important chemicals (NH3). However, it is still a great challenge to prepare catalysts with excellent NO3- adsorption/activation capacity to achieve high NITRR. Herein, we designed a novel Fe2+Cu2+Fe3+LDH/BiVO4 (FCF-LDH/BVO) catalyst with synergistic effect of chemical adsorption and physical enrichment. Fe2+ in FCF-LDH/BVO provides the rich Lewis acid sites for the adsorption of NO3-, and the appropriate layer spacing of FCF-LDH further promotes the physical enrichment of NO3- in its interior, thus realizing the effective contact between NO3- and active sites (Fe2+). FCF-LDH/BVO showed excellent NH3 production performance (FENH3= 66.1%, rNH3 = 13.8 μg h-1 cm-2) and selectivity (FENO2- = 2.5%, rNO2- = 4.9 μg h-1 cm-2) in 0.5 mol L-1 Na2SO4 electrolyte. In addition, FCF-LDH/BVO maintains the desirable PEC stability for six cycle experiments, showing great potential for practical application. The 14NO3- and 15NO3- isotope test provides strong evidence for further verification of the origin of N in the generated NH3. This LDH catalyst has a great potential in PEC removal of NO3- from groundwater.
Abstract:
Developing the alternative supported noble metal catalysts with low cost, high catalytic efficiency, and good resistance toward carbon dioxide and water vapor is critically demanded for the oxidative removal of volatile organic compounds (VOCs). In this work, we prepared the mesoporous chromia-supported bimetallic Co and Ni single-atom (Co1Ni1/meso-Cr2O3) and bimetallic Co and Ni nanoparticle (CoNPNiNP/meso-Cr2O3) catalysts adopting the one-pot polyvinyl pyrrolidone (PVP)- and polyvinyl alcohol (PVA)-protecting approaches, respectively. The results indicate that the Co1Ni1/meso-Cr2O3 catalyst exhibited the best catalytic activity for n-hexane (C6H14) combustion (T50% and T90% were 239 and 263 ℃ at a space velocity of 40,000 mL g-1 h-1; apparent activation energy and specific reaction rate at 260 ℃ were 54.7 kJ mol-1 and 4.3×10-7 mol gcat-1 s-1, respectively), which was associated with its higher (Cr5+ + Cr6+) amount, large n-hexane adsorption capacity, and good lattice oxygen mobility that could enhance the deep oxidation of n-hexane, in which Ni1 was beneficial for the enhancements in surface lattice oxygen mobility and low-temperature reducibility, while Co1 preferred to generate higher contents of the high-valence states of chromium and surface oxygen species as well as adsorption and activation of n-hexane. n-Hexane combustion takes place via the Mars-van Krevelen (MvK) mechanism, and its reaction pathways are as follows: n-hexane → olefins or 3-hexyl hydroperoxide → 3-hexanone, 2-hexanone or 2,5-dimethyltetrahydrofuran → 2-methyloxirane or 2-ethyl-oxetane → acrylic acid → COx → CO2 and H2O.
Abstract:
It is of great scientific and economic value to recycle waste poly (ethylene terephthalate) (PET) into high-value PET-based metal organic frameworks (MOFs) and further convert it into porous carbon for green energy storage applications. In the present study, a facile and cost-effective hydrothermal process was developed to direct recycle waste PET bottles into MIL-53(Al) with a 100% conversation, then the MOF-derived porous carbon was assembled into electrodes for high-performance supercapacitors. The results indicated that the as-synthesized carbon exhibited high SSA of 1712 m2 g-1 and unique accordion-like structure with hierarchical porosity. Benefit to these advantageous characters, the assembled three-electrode supercapacitor displayed high specific capacitances of 391 F g-1 at the current density of 0.5 A g-1 and good rate capability of 73.6% capacitance retention at 20 A g-1 in 6 mol L-1 KOH electrolyte. Furthermore, the assembled zinc ion capacitor still revealed outstanding capacitance of 335 F g-1 at 0.1 A g-1, excellent cycling stability of 92.2% capacitance retention after 10 000 cycles and ultra-high energy density of 150.3 Wh kg-1 at power density of 90 W kg-1 in 3 mol L-1 ZnSO4 electrolyte. It is believed that the current work provides a facile and effective strategy to recycle PET waste into high-valuable MOF, and further expands the applications of MOF-derived carbons for high-performance energy storage devices, so it is conducive to both pollution alleviation and sustainable economic development.
Abstract:
Developing highly active oxygen evolution reaction (OER) electrocatalysts with robust durability is essential in producing high-purity hydrogen through water electrolysis. Layered double hydroxide (LDH) based catalysts have demonstrated efficient catalytic performance toward the relatively sluggish OER. By considering the promotion effect of phosphate (Pi) on proton transfer, herein, a facile phosphate acid (PA) surface-neutralization strategy is developed to in-situ construct NiCo-LDH/NiCoPi hetero-sheets toward OER catalysis. OER activity of NiCo-LDH is significantly boosted due to the proton promotion effect and the electronic modulation effect of NiCoPi. As a result, the facilely prepared NiCo-LDH/NiCoPi catalyst displays superior OER catalytic activity with a low overpotential of 300 mV to deliver 100 mA cm-2 OER and a Tafel slope of 73 mV dec-1. Furthermore, no visible activity decay is detected after a 200-h continuous OER operation. The present work, therefore, provides a promising strategy to exploit robust OER electrocatalysts for commercial water electrolysers.
Abstract:
This work uses thermal polymerization of urea nitrate, oxyacetic acid and urea as the raw material to prepare ultra-thin porous carbon nitride with carbon defects and C–O band (OA-UN-CN). Density functional theory (DFT) calculations showed OA-UN-CN had narrower band gap, faster electron transport and a new internal construction electric field. Additionally, the prepared OA-UN-CN significantly enhanced photocatalytic activation of peroxymonosulfate (PMS) due to enhanced light absorption performance and faster electron overflow. As the result, the OA-UN-CN/PMS could entirely degrade bisphenol A (BPA) within 30 min, where the photodegradation rate was 81.8 and 7.9 times higher than that of g-C3N4 and OA-UN-CN, respectively. Beyond, the OA-UN-CN/PMS could likewise degrade other bisphenol pollutants and sodium lignosulfonate efficiently. We suggested possible photocatalytic degradation pathways accordingly and explored the toxicity of its degradation products. This work provides a new idea on the development of advanced photocatalytic oxidation processes for the treatment of bisphenol pollutants and lignin derivatives, via a metal-free photothermal-catalyst.
Abstract:
Defect engineering is an effective strategy for modifying the energy storage materials to improve their electrochemical performance. However, the impact of oxygen defect and its content on the electrochemical performances in the burgeoning aqueous NH4+ storage field remains explored. Therefore, for the first time in this work, an oxygen-defective ammonium vanadate [(NH4)2V10O25·8H2O, denoted as Od-NHVO] with a novel 3D porous flower-like architecture was achieved via the reduction of thiourea in a mild reaction condition, which is a facile method that can realize the intention to regulate the oxygen defect content, with the capability of mass-production. The as-prepared OdM-NHVO with moderate oxygen defect content can deliver a stable specific capacitance output (505 F g-1, 252 mAh g-1 at 0.5 A g-1 with ~80% capacitance retention after 10,000 cycles), which benefits from extra active sites, unimpeded NH4+-migration path and relatively high structure integrity. In contrast, low oxygen defect content will lead to the torpid electrochemical reaction kinetics while too high content of it will reduce the charge-storage capability and induce structural disintegration. The superior NH4+-storage behavior is achieved with the reversible intercalation/de-intercalation process of NH4+ accompanied by forming/breaking of hydrogen bond. As expected, the assembled flexible OdM-NHVO//PTCDI quasi-solid-state hybrid supercapacitor (FQSS HSC) also exhibits high areal capacitance, energy density and reliable flexibility. This work provides a new avenue for developing materials with oxygen-deficient structure for application in various aqueous non-metal cation storage systems.
Abstract:
Aluminum (Al), the most abundant metallic element on the earth crust, has been reckoned as a promising battery material for its the highest theoretical volume capacity (8046 mAh cm-3). Being rechargeable in ionic liquid electrolytes, however, the Al anode and battery case suffer from corrosion. On the other hand, Al is irreversible in aqueous electrolyte with severe hydrogen evolution reaction. Here, we demonstrate a water-in-salt aluminum ion electrolyte (WISE) based on Al and lithium salts to tackle the above challenges. In the WISE system, water molecules can be confined within the Li+ solvation structures. This diminished Al3+-H2O interaction essentially eliminates the hydrolysis effect, effectively protecting Al anode from corrosion. Therefore, long-term Al plating/stripping can be realized. Furthermore, two types of high-performance full batteries have been demonstrated using copper hexacyanoferrate (CuHCF, a Prussian Blue Analogues) and LiNi0.8Co0.1Mn0.1O2 (NCM) as cathodes. The reversibility of Al anode laid the foundation for low cost rechargeable batteries suffering for large-scale energy storage.
Broader context: Al batteries are expected to become a safe and sustainable alternative to lithium batteries. For decades, chase for a feasible Al secondary battery has not been successful. The key challenge is to find suitable cathode and electrolyte materials, together with which Al anode battery can function reversibly. Currently, fatal drawbacks have impeded the practical application of Al metal batteries (AMBs), such as sustained corrosion of Al anode and battery case in ionic liquid electrolytes, irreversibility issues as well as severe hydrogen evolution reaction during cycling in aqueous electrolyte. Therefore, electrolyte and their electrochemical kinetics play a vital role in the performance and environmental operating limitations of high-energy Al metal batteries. In this work, we demonstrate a nearly neutral Al ion water-in-salt electrolyte (WISE) to tackle the above challenges. The WISE shows excellent stability in the open atmosphere. The distinct solvation-sheath structure of Al3+ in the WISE system would protect Al metal anodes from corrosion and eliminate hydrogen evolution reaction effectively, further promoting the reversibility of Al metal anodes with dendrite-free morphology. Moreover, such a WISE exhibits superior compatibility with LiNi0.3Co0.3Mn0.3O2 (NCM) and copper hexacyanoferrate (CuHCF) cathodes and long-term stabilities with high coulombic efficiency (CE) can be attained for full batteries with the WISE. The approach in this study can furnish an opportunity to develop reversible AMBs and lay the foundation for other potential multivalent-metal-based secondary batteries suffering from interface passivation and poor reversibility, which suggest the promise of multivalent metal batteries and their applications in large-scale energy storage.