The Front Cover highlights the deep eutectic solvent (DES)-optimized preparation through hydrogen bond acceptor and donor interactions between various molecules of pharmaceutical interest for personalized medicine. Indeed, the choice of the DES chemical components is influenced not only by their intrinsic properties but also by their intended therapeutic use after the components’ association. In the Review article, more insights regarding the different approaches to conveniently selecting the constituents of DESs, from physico-chemical concerns to engineered therapeutic eco-friendly materials, are raised. More information can be found in the Review by F. Oyoun et al.

The achievement of the outstanding theoretical capacitance of nickel sulfide (NiS2) is challenging due to its low conductivity, slow electrochemical kinetics, and poor structural stability. In this study, we utilize polyaniline (PANI) as a linker to anchor the NiS2 with a hollow bowl-like structure, uniformly dispersed at the surface of graphene oxide (GO)(NiS2@15PG). The presence of PANI provides growth sites, resulting in a uniform and dense arrangement of NiS2. This morphological modulation of NiS2 increases the contact area between the active material to electrolyte. Additionally, PANI effectively connects NiS2 with the conductive network of GO, which advances the electrical conductivity and ion diffusion properties. As a result, the Rct (charge transfer resistance) and Zw (Warburg impedance) of NiS2@15PG decrease by 82.61% and 66.76% respectively. This unique structure confers NiS2@15PG with high specific capacitance (536.13 C g-1 at 1 A g-1) and excellent multiplicative property of 60.93% at 20 A g-1. The assembled NiS2@15PG//YP-50 supercapacitors (HSC) demonstrate an energy density (13.09 Wh kg-1) at a high-power density (16000 W kg-1). The capacity retention after 10,000 cycles at 5 A g-1 is 86.59%, indicating its significant potential for practical applications.

To cope with climate change issues, a significant shift is required in worldwide energy sources. Hydrogen and bioenergy are being considered as alternatives toward a carbon neutral society, making formic acid—a hydrogen carrying product of glycerol—of interest for the valorization of glycerol. Here we investigate the plasma-induced transformation of glycerol in an aqueous nanosecond repetitively pulsed discharge reactor. We found that the water content in the aqueous mixture fulfilled a crucial role in both the gas phase (as a source of OH radicals) and the liquid phase (as a promotor of the dissolved OH radical’s mobility and reactivity). The formic acid produced was linearly proportional to the specific input energy, and the most cost-effective production of formic acid was found with 10-%v/v glycerol in the aqueous mixture. A plausible reaction pathway was proposed, consisting of the OH radical-driven dehydrogenation and dehydration of glycerol. The results provide a fundamental understanding of plasma-induced transformation of glycerol to formic acid and insights for future practical applications.

Picture showing ammonia synthesis reaction over W substituted cobalt molybdenum nitride in relation to the potential discovery of new catalyst formulations with higher activity.

Abstract

The effect of the partial substitution of Mo with W in Co₃Mo₃N and Ni₂Mo₃N on ammonia synthesis activity and lattice nitrogen reactivity has been investigated. This is of interest as the coordination environment of lattice N is changed by this process. When tungsten was introduced into the metal nitrides by substitution of Mo atoms, the catalytic performance was observed to have decreased. As expected, Co₃Mo₃N was reduced to Co₆Mo₆N under a 3 : 1 ratio of H₂/Ar. Co₃Mo_2.6W_0.4N was also shown to lose a large percentage of lattice nitrogen under these conditions. The bulk lattice nitrogen in Ni₂Mo₃N and Ni₂Mo_2.8W_0.2N was unreactive, demonstrating that substitution with tungsten does not have a significant effect on lattice N reactivity. Computational calculations reveal that the vacancy formation energy for Ni₂Mo₃N is more endothermic than Co₃Mo₃N. Furthermore, calculations suggest that the inclusion of W does not have a substantial impact on the surface N vacancy formation energy or the N₂ adsorption and activation at the vacancy site.

Herein we report a potential catalyst capable of electrochemical formation of ammonia at standard temperature and pressure. The activity of (100) rocksalt transition metal carbide (TMC) surfaces was tested via density functional theory computational calculations following the unrestricted mechanism. Results indicate that some of the TMC catalysts could be capable of efficient electrochemical ammonia formation and that activity is greatly enhanced in the presence of a surface carbon vacancy.

Abstract

The development of a low-cost, energy-efficient, and environmentally friendly alternative to the currently utilized Haber-Bosch process to produce ammonia is of great importance. Ammonia is an essential chemical used in fertilizers and a promising high-density fuel source. The nitrogen reduction reaction (NRR) has been explored intensively as a potential avenue for ammonia production using water as proton source, but to this day a catalyst capable of producing this chemical at high Faradaic efficiency (FE) and commercial yield and rates has not been reported. Here, we investigate the activity of transition metal carbide (TMC) surfaces in the (100) facets of the rocksalt (RS) structure as potential catalysts for the NRR. In this study, we use density functional theory (DFT) to model reaction pathways, estimate stability, assess kinetic barriers, and compare adsorbate energies to determine the overall performance of each TMC surface. For pristine TMC surfaces (with no defects) we find that none of the studied TMCs possess both exergonic adsorption of nitrogen and the capability to selectively protonate nitrogen to form ammonia in the desired aqueous solution. ZrC, however, is shown to be a potential catalyst if used in a non-aqueous electrolyte. To circumvent the endergonic adsorption of nitrogen onto the surface, a carbon vacancy was introduced. This provides a well-defined high coordination active site on the surface. In the presence of a vacancy VC, NbC, and WC showed efficient nitrogen adsorption, selectivity towards ammonia, and a low overpotential (OP). NbC did, however, display an unfeasible kinetic barrier to nitrogen dissociation for ambient-condition purposes, and thus it is suggested for high tempearture/pressure ammonia synthesis. Both WC and VC in their RS (100) structure are promising materials for experimental investigations in aqueous electrolytes, and ZrC could potentially be interesting for non-aqueous electrolytic systems.

In the course of the UOR process, the presence of Li⁺ led to an increase in the Faradaic efficiency (FE) of the innocuous N₂ product from the standard value of ~15 % to 45 % compared with K⁺, while a decrease of the FEs of the over-oxidized NO _x ⁻ product from ~80 % to 46 %, indicating a more eco-friendly and sustainable process under the cation effect.

Abstract

Urea electrolysis is an emerging technology that bridges efficient wastewater treatment and hydrogen production with lower electricity costs. However, conventional Ni-based catalysts could easily overoxidize urea into the secondary contaminant NO _x ⁻, and enhancing the innocuity of urea electrolysis remains a grand challenge to be achieved. Herein, we tailored the electrode-electrolyte interface of an unconventional cation effect on the anodic oxidation of urea to regulate its activity and selectivity. Smaller cations of Li⁺ were discovered to increase the Faradaic efficiency (FE) of the innocuous N₂ product from the standard value of ~15 % to 45 %, while decreasing the FEs of the over-oxidized NO _x ⁻ product from ~80 % to 46 %, pointing to a more sustainable process. The kinetic and computational analysis revealed the dominant residence of cations on the outer Helmholtz layer, which forms the interactions with the surface adsorbates. The Li⁺ hydration shells and rigid hydrogen bonding network interact strongly with the adsorbed urea to decrease its adsorption energy and subjection to C−N cleavage, thereby directing it toward the N₂ pathway. This work emphasizes the tuning of the interactions within the electrode-electrolyte interface for enhancing the efficiency and sustainability of electrocatalytic processes.

The obtained CuS nanoparticles is a good candidate for CO₂ electroreduction to formate with high FE (~98 %). The reconstruction of CuS with S loss in the form of H₂S, SO₂, and SO₄ ²⁻ during the reaction induces the degradation of the catalytic performance on CO₂ electroreduction to formate.

Abstract

CO₂ electroreduction into liquid fuels is of broad interest and benefits reducing the energy crisis and environment burdens. CuS has been reported to be a desirable candidate for CO₂ electroreduction into formate; however, its formate selectivity and stability are still far from the demands of practical application. Herein, we report CuS nanoparticles exhibiting good Faradaic efficiency of formate (about 98 %) in CO₂ electroreduction and its deactivation mechanism during the reaction. The deactivation of CuS was found to be associated with the reconstruction and S loss of CuS, which deteriorates the Faradaic efficiency of formate. Combined with ionic and gas analyses, the S atom in CuS was lost in the form of H₂S, SO₂, and SO₄ ²⁻, followed by the reconstruction of CuS into copper oxides. Such a catalyst reconstruction facilitates electroreductions of CO₂ and H₂O, respectively, into CO and H₂, etc., resulting in the degradation of catalytical performance of CO₂ electroreduction into formate. This work reveals the important role of S loss and reconstruction of metal sulfide catalysts during the electroreduction reaction, which may benefit the further development of CuS-based electro-catalyst for CO₂ electroreduction.

Plastic waste is a promising and abundant resource for H2 production. However, upcycling plastic waste into H2 fuel via conventional thermochemical routes requires relatively considerable energy input and severe reaction conditions, particularly for polyolefin waste. Here, we report a tandem strategy for the selective upcycling of polypropylene (PP) waste into H2 fuel in a mild and clean manner. PP waste was first oxidized into small-molecule organic acids using pure O2 as oxidant at 190 °C, followed by the catalytic reforming of oxidation aqueous products over ZnO–modified Ru/NiAl2O4 catalysts to produce H2 at 300 °C. A high H2 yield of 44.5 mol/kgPP and a H2 mole fraction of 60.5% were obtained from this tandem process. The entire process operated with almost no solid residue remaining and equipment contamination, ensuring relative stability and clean of the reaction system. This strategy provides a new route for low-temperature transforming PP and improving the sustainability of plastic waste disposal processes.

Lignin nanoparticles (LNPs) are promising components for various materials, given their controllable particle size and spherical shape. However, their origin from supramolecular aggregation has limited the applicability of LNPs as recoverable templates for immobilization of enzymes. In this study, we show that stabilized LNPs are highly promising for the immobilization of phospholipase D (PLD), the enzyme involved in the biocatalytic production of high-value polar head modified phospholipids of commercial interest, phosphatidylglycerol, phosphatidylserine and phosphatidyl-ethanolamine. Starting from hydroxymethylated lignin, LNPs were prepared and successively hydrothermally treated to obtain c-HLNPs with high resistance to organic solvents and a wide range of pH values, covering the conditions for enzymatic reactions and enzyme recovery. The immobilization of PLD on c-HLNPs (PLD-c-HLNPs) was achieved through direct adsorption. We then successfully exploited this new enzymatic preparation in the preparation of pure polar head modified phospholipids with high yields (60-90%). Furthermore, the high PLD-c-HLNPs stability allows its recycling for a number of reactions with appreciable maintenance of its catalytic activity. Thus, PLD-c-HLNPs can be regarded as a new, chemically stable, recyclable and user-friendly biocatalyst, based on a biobased inexpensive scaffold, to be employed in sustainable chemical processes for synthesis of value-added phospholipids.

Ionic liquids can do more! A facile and efficient self-assembled [HOEtMIM]Cl layer is introduced for the first time in the rigid and flexible electron transport layer-free perovskite solar cells, giving rise an improved power conversion efficiency of 19.60 % and 15.57 %, along with an improved hysteresis and stability.

Abstract

The advancement of electron transport layer (ETL)-free perovskite solar cells (PSCs) is crucial for the commercialization of PSCs. At present, the slow electron extraction and significant carrier recombination, related to the energy-level alignment at the FTO/perovskite interface, restrict the performance of ETL-free PSCs. The facile modification of bottom electrodes is pivotal for tackling these issues and stimulating the photovoltaic potential of perovskite. Herein, a cost-competitive and neoteric 1-hydroxyethyl-3-methylimidazolium chloride, [HOEtMIM]Cl, ionic liquid is employed to modify the surface of rigid and flexible electrodes, and thus enable an energetically well-aligned interface with perovskite layer via the electric dipole effects. The resulting barrier-free FTO/perovskite contact can tremendously ameliorate the electron extraction and collection, with mitigated nonradiative interfacial carrier recombination loss. Additionally, the lone pair on the nitrogen of the imidazole group passivates the surface defects of perovskite layers, and the chloride anion plays a role in the crystallinity improvement of perovskite. Leveraged by the [HOEtMIM]Cl modification, the resulting ETL-free rigid and flexible devices deliver an outstanding power conversion efficiency of 19.60 % and 15.57 %, along with the ameliorated hysteresis and long-term tenability. This finding highlights the drastic potential of the engineered [HOEtMIM]Cl in manufacturing stable and high-performance ETL-free PSCs for their scaled-up production.