Metal-Free Boron/Phosphorus Co-Doped Nanoporous Carbon for Highly Efficient Benzyl Alcohol Oxidation

Entropy-Driven Competitive Adsorption Sites Tailoring Unlocks Efficient Hybrid Conversion Zn-Air Batteries

Hybrid conversion Zn-air batteries (HC-ZABs) epitomize a typical integrated energy storage and conversion device that advances green chemistry and reduces carbon emissions. However, balancing efficiency and selectivity of electrocatalytic cathodic reactions remains the bottleneck in such batteries. Herein, we address this issue by designing a high-entropy perovskite, La0.6Sr0.1Ca0.1Rb0.1Y0.1CoO3 (HE-LCO), which outperforms conventional perovskites in offering enhanced electrocatalytic activity, better selectivity, and outstanding stability for cathodic benzyl alcohol oxidation reaction (BAOR). Combined spectroscopy characterizations, operando measurements, and theoretic calculations reveal that the entropy-driven modulation of the second coordination sphere in HE-LCO balances the adsorption of nucleophile benzyl alcohol and OH-, while inhibiting competing oxygen evolution reaction (OER). Based on this rationalized HE-LCO electrocatalyst, HC-ZABs realized efficient energy storage and benzoic acid production, boasting a long lifespan of 900 cycles at 20 mA cm-2 and 6.7 mAh cm-2 per cycle. Further, practical ampere-hour-scale HC-ZABs demonstrated a 62.8% energy efficiency improvement and an average benzoic acid yield of 0.85 g per cycle, highlighting the potential of this integrated device for simultaneous sustainable energy storage and green electrochemical synthesis.

Metal-Free N, P-Codoped Carbon for Syngas Production with Tunable Composition via CO2 Electrolysis: Addressing the Competition Between CO2 Reduction and H2 Evolution

Electroreduction of carbon dioxide into value-added fine chemicals is a promising technique to realize the carbon cycle. Recently, metal-free heteroatom doped carbons are proposed as promising cost-effective electrocatalysts for CO2 reduction reaction (CO2RR). However, the lack of understanding of the active site prevents the realization of a high-performance electrocatalyst for the CO2RR. Herein, we synthesized metal-free N, P co-doped carbons (NPCs) for producing syngas, which is composed of H2 and CO, by CO2 electrolysis using inexpensive bio-based raw materials via simple pyrolysis. The syngas ratio (H2/CO) can be controlled within the high demand range (0.3-4) at low potentials using NPCs by tuning the N and P contents. In comparison with only N doping or P doping, N and P co-doping has a positive impact on improving CO2RR activity. Experimental analysis and density functional theory (DFT) calculations revealed that negatively charged C atoms adjacent to N and P atoms are the most favorable active sites for CO2-to-CO conversion compared to pyridinic N on N, P co-doped carbon. Introducing N atoms generates the preferable CO2 adsorption site, and P atoms contribute to decreasing the Gibbs free energy barrier for key *COOH intermediates adsorbed on the negatively charged C atoms.

Fabrication of Graphene Polyhedra: Unveiling New Structures, Forms, and Properties

A hybrid nanoporous carbon alloy material is synthesized using a core-shell structure based on metal-organic frameworks, revealing a novel graphene polyhedral form. The presence of carbon and metal as doped cobalt carbides based on morphed graphene within the graphene polyhedra is confirmed through a combination of X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and Raman spectroscopy analyses. These novel graphene polyhedra exhibit magnetoelectric coupling properties at room temperature. The magnetic state control is verified using a magnetic probe; the changes in the magnetic state increased with a higher applied bias, and the poling direction of the magnetic phase is reversed based on the scanning direction of the probe. This discovery holds promise for future applications in ultrafast devices and carbon-based spintronics research.

Ecofriendly metal-free olefins epoxidation and alcohol oxidation by in situ generated poly(peroxybenzoic acid) as a heterogeneous recyclable catalyst under mild conditions: an in-depth mechanistic study

In this study a mild and selective protocol was introduced for the alcohol oxidation and alkene epoxidation as two vital reactions in organic synthesis. Poly(benzoic acid) (PBA), a synthetic polymer, was used for the preparation of highly active poly(peroxybenzoic acid) (PPBA) in situ in the presence of H2O2. At ambient temperature, alcohol (primary) oxidation proceeds to carboxylic acid selectively (81-99% selectivity), and in 0 °C, aldehyde was the selective product (90-98% selectivity). Alkene epoxidation was also performed in 0 °C with high selectivity. The catalyst was compatible towards a wide variety of alcohols and alkenes substrates like acid sensitive substrates. PBA is used in the reaction at a catalytic rate and, in the presence of H2O2, which provides the oxygen necessary for oxidation, is converted to catalytically active PPBA species and reintroduced into the catalytic cycle. The mechanism of the oxidation and epoxidation processes was studied deeply. PBA could be recycled for several times without loss of catalytic activity.

Balancing Competitive Adsorption on Co3O4@P, N-Doped Porous Carbon to Enhance the Electrocatalytic Upgrading of Biomass Derivatives

The electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) represents an environmentally friendly approach to generate high-value-added chemicals from biomass. The successful electrochemical transformation of HMF during the oxidation reaction (HMFOR) necessitates an ideal adsorption interaction between HMF and OH- on the electrode surface. Yet, catalysts with a singular active site offer limited flexibility in managing the competitive adsorption of HMF and OH-. To this end, different active sites are customized in this work to construct a P and N co-doped porous carbon that wrapped Co3O4 (Co3O4@PNC). Co-doping with these two heteroatoms generates C3P = O and pyrrolic N as adsorption sites to better balance the adsorption of HMF and OH-, respectively, rather than promoting competition between the HMF and OH- on a single active site. With this design strategy, Co3O4@PNC demonstrates significant HMFOR activity, the conversion rate of HMF surpassed 99% with a 2,5-furandicarboxylic acid (FDCA) yield exceeding 95% after 2 h of electrolysis. Furthermore, it shows universal applicability in the electrooxidation of other alcohol/aldehyde substrates, yielding efficiencies of 90-99%. This work not only provides guidance for advanced electrocatalysts design toward alcohol/aldehyde oxidation but also offers insights into the utilization of biomass-derived platform chemicals.

Biomolecule-derived three-dimensional N, P co-doped carbon nanosheets for the efficient oxidative dehydrogenation of propane

Non-metallic heteroatom-doped carbon materials are promising catalysts for the oxidative dehydrogenation of propane (ODHP), but their controlled synthesis remains challenging. Herein, a novel three-dimensional N, P co-doped carbon nanosheet (NPC-NS-T) catalyst is prepared, which shows an impressive catalytic performance in the ODHP reaction with high propane conversion (20.0%) and high selectivity for propene (62.1%) and olefins (64.5%) at 500 °C along with good long-time stability. Comprehensive experimental characterizations revealed that incorporation of appropriate P can not only help to form more CO species on the surface of NPC-NS-T but also inhibit the consumption of CO species under ODHP conditions, thereby remarkably improving the catalytic performance. This work could pave the way for developing efficient biomass-derived carbon catalysts for the oxidative dehydrogenation reactions of propane.

Novel insights on room temperature-induced cellulose dissolution mechanism via ZnCl2 aqueous solution: Migration, penetration, interaction, and dispersion

The unique molecular structure of cellulose makes it challenging to dissolve at room temperature (R.T.), and the dissolution mechanism remains unclear. In this study, we employed ZnCl2 aqueous solution for cellulose dissolution at R.T., proposing a novel four-stage dissolution mechanism. The efficient dissolution of cellulose in ZnCl2 aqueous solution at R.T. involves four indispensable stages: rapid migration of hydrated Zn2+ ions towards cellulose, sufficient penetration between cellulose sheets, strong interaction with cellulose hydroxyl groups, and effective dispersion of separated cellulose chains. The proposed four-stage dissolution mechanism was validated through theoretical calculations and experimental evidence. The hydrated Zn2+ ions in ZnCl2 + 3.5H2O solvent exhibited ideal migration, penetration, interaction, and dispersion abilities, resulting in efficient cellulose dissolution at R.T. Moreover, only slight degradation of cellulose occurred in ZnCl2 + 3.5H2O at R.T. Consequently, the regenerated cellulose materials obtained from ZnCl2 + 3.5H2O (R.T.) exhibited better mechanical properties. Notably, the solvent recovery rate reached about 95 % based on previous usage during five cycles. The solvent is outstanding for its green, low-cost, efficiency, simplicity, R.T. conditions and recyclability. This work contributes to a better understanding of the cellulose dissolution mechanisms within inorganic salt solvents at R.T., thereby guiding future development efforts towards greener and more efficient cellulosic solvents.

Glycosidic bond protection of cellulose during solvent dissolution by coordination interaction competition strategy

Exploiting new solvents on efficiently dissolving cellulose is imperative to promote the utilization of cellulosic resources. The process of cellulose dissolution typically necessitates extreme conditions, such as high-temperature treatment, utilization of potent acidic or basic solvents, or the catalytic action of Lewis acids. As a result, the structure of the cellulose is invariably compromised, subsequently obstructing the creation of high-performance materials. In this study, we address this challenge through a simple process, introducing polyethylene glycol (PEG) as glycosidic bond protecting agent, to preserve the polymerization degree of cellulose during its room-temperature dissolution in ZnCl2-phosporic acid eutectic solvent. The PEG units preferentially coordinate with Zn2+ to weaken the hydrolysis of glycosidic bond of cellulose through ether bond competition. The polymerization degree of regenerated cellulose is thus greatly improved, reaching up to seven times that of unprotected cellulose. Overall, this study offers an easy and cost-effective approach to develop cellulose solvents and provides a significant drive towards the fabrication of practical materials through cellulose dissolution.

Electrocatalytic Lignin Valorization into Aromatic Products via Oxidative Cleavage of Cα-Cβ Bonds

Lignin is the most promising candidate for producing aromatic compounds from biomass. However, the challenge lies in the cleavage of C-C bonds between lignin monomers under mild conditions, as these bonds have high dissociation energy. Electrochemical oxidation, which allows for mild cleavage of C-C bonds, is considered an attractive solution. To achieve low-energy consumption in the valorization of lignin, the use of highly efficient electrocatalysts is essential. In this study, a meticulously designed catalyst consisting of cobalt-doped nickel (oxy)hydroxide on molybdenum disulfide heterojunction was developed. The presence of molybdenum in a high valence state promoted the adsorption of tert-butyl hydroperoxide, leading to the formation of critical radical intermediates. In addition, the incorporation of cobalt doping regulated the electronic structure of nickel, resulting in a lower energy barrier. As a result, the heterojunction catalyst demonstrated a selectivity of 85.36% for cleaving the Cα-Cβ bond in lignin model compound, achieving a substrate conversion of 93.69% under ambient conditions. In addition, the electrocatalyst depolymerized 49.82 wt% of soluble fractions from organosolv lignin (OL), resulting in a yield of up to 13 wt% of aromatic monomers. Significantly, the effectiveness of the prepared electrocatalyst was also demonstrated using industrial Kraft lignin (KL). Therefore, this research offers a practical approach for implementing electrocatalytic oxidation in lignin refining.

Heteroatom Codoped Graphene: The Importance of Nitrogen

Although graphene has exceptional properties, they are not enough to solve the extensive list of pressing world problems. The substitutional doping of graphene using heteroatoms is one of the preferred methods to adjust the physicochemical properties of graphene. Much effort has been made to dope graphene using a single dopant. However, in recent years, substantial efforts have been made to dope graphene using two or more dopants. This review summarizes all the hard work done to synthesize, characterize, and develop new technologies using codoped, tridoped, and quaternary doped graphene. First, I discuss a simple question that has a complicated answer: When can an atom be considered a dopant? Then, I briefly discuss the single atom doped graphene as a starting point for this review's primary objective: codoped or dual-doped graphene. I extend the discussion to include tridoped and quaternary doped graphene. I review most of the systems that have been synthesized or studied theoretically and the areas in which they have been used to develop new technologies. Finally, I discuss the challenges and prospects that will shape the future of this fascinating field. It will be shown that most of the graphene systems that have been reported involve the use of nitrogen, and much effort is needed to develop codoped graphene systems that do not rely on the stabilizing effects of nitrogen. I expect that this review will contribute to introducing more researchers to this fascinating field and enlarge the list of codoped graphene systems that have been synthesized.

Recent progresses on single-atom catalysts for the removal of air pollutants

The booming industrialization has aggravated emission of air pollutants, inflicting serious harm on environment and human health. Supported noble-metals are one of the most popular catalysts for the oxidation removal of air pollutants. Unfortunately, the high price and large consumption restrict their development and practical application. Single-atom catalysts (SACs) emerge and offer an optimizing approach to address this issue. Due to maximal atom utilization, tunable coordination and electron environment and strong metal-support interaction, SACs have shown remarkable catalytic performance on many reactions. Over the last decade, great potential of SACs has been witnessed in the elimination of air pollutants. In this review, we first briefly summarize the synthesis methods and modulation strategies together with the characterization techniques of SACs. Next, we highlight the application of SACs in the abatement of air pollutants including CO, volatile organic compounds (VOCs) and NOx, unveiling the related catalytic mechanism of SACs. Finally, we propose the remaining challenges and future perspectives of SACs in fundamental research and practical application in the field of air pollutant removal.