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Zn-air batteries are a highly promising clean energy sustainable conversion technology, and the design of dual-function electrocatalysts with excellent activity and stability is crucial for their development. In this work, FeCo alloy loaded biomass-based N and S co-doped carbon aerogels (FeCo@NS-LCA) were fabricated from chitosan and lignosulfonate-metal chelates via liquid nitrogen pre-frozen synergistic high-temperature carbonization with application in electrocatalytic reactions. The abundant oxygen-containing functional groups on lignosulfonates have a chelating effect on metal ions, which can avoid the aggregation of metal nanoparticles during carbonation and catalysis, facilitating the construction of a nanoconfinement catalytic system with biomass carbon as the domain-limiting body and FeCo nanoparticles as the active sites. FeCo@NS-LCA exhibited catalytic activity (E 1/2 = 0.87 V, J L = 5.7 mA cm−2) comparable to the commercial Pt/C in the oxygen reduction reaction (ORR), excellent resistance to methanol toxicity and stability. Meanwhile, the overpotential of oxygen evolution reaction (OER) was 324 mV, close to that of commercial RuO 2 catalysts (351 mV). This study utilizes the coordination action of lignosulfonate to provide a novel and environmentally friendly method for the preparation of confined nano-catalysts and provides a new perspective for the high-value utilization of biomass resources. [Display omitted] [ABSTRACT FROM AUTHOR]

A novel S-scheme heterojunction of Cs 3 Mo x Sb y Br 9 /BiVO 4 has been developed for the photocatalytic coupling of N 2 fixation and H 2 O oxidation. It presents a simultaneous enhancement for redox capacities, exhibiting excellent photocatalytic N 2 reduction to NH 3 activity (300 μmol g−1 h−1) under simulated solar light illumination (100 mW cm−2). [Display omitted] • This work marks the inaugural utilization of lead-free halide perovskite in photocatalytic N 2 fixation. • Attributing to the electronic structure regulation and S-scheme heterojunction design, Cs 3 Mo x Sb y Br 9 /BiVO 4 achieves efficient N 2 photoreduction with H 2 O as the electron source. • The photocatalytic mechanism is explored through theoretical calculation and in-situ characterization. Synergistic nitrogen (N 2) reduction with water (H 2 O) oxidation is meaningful but challenging owing to the inertness of the N 2 molecule and the sluggish kinetics of H 2 O oxidation. Herein, a simutaneous-promotion strategy of redox capacities is presented for constructing a lead-free Cs 3 Sb 2 Br 9 -based S-scheme heterojunction, by decorating Mo-functionalized Cs 3 Sb 2 Br 9 nanocrystals (Cs 3 Mo x Sb y Br 9) on BiVO 4 nanosheet through an in-situ plane-to-point growth manner. The Mo-functionalization for Cs 3 Sb 2 Br 9 enables the regulation of the d-band center position, greatly improving surface reaction kinetics for N 2 reduction. Furthermore, the construction of the S-scheme heterojunction enhances the driving force for H 2 O oxidation and spatial charge separation of photocatalysts. As anticipated, the resultant Cs 3 Mo x Sb y Br 9 /BiVO 4 exhibits an excellent photocatalytic N 2 reduction activity under ambient atmosphere, achieving ammonia (NH 3) production at a rate of 300 ± 5 μmol g−1 h−1 under simulated sunlight illumination (100 mW cm−2), which is nearly 20-fold higher than that of pristine Cs 3 Sb 2 Br 9. [ABSTRACT FROM AUTHOR]

The development of metal-free electrocatalytic materials that are economical, friendly to the environment, and efficiency towards the oxygen reduction reaction (ORR) is of significant interest. Hence, this paper synthesizes nitrogen and sulfur co-doped three-dimensional magnesium lignosulfonate (MLS-derived) flower-like hierarchical porous carbon (NSLPC) materials by a simple and green method. The synthesized NSLPC uses magnesium lignosulfonate as the sulfur source and carbon precursor, melamine as nitrogen source, MgO as hard template, and ZnCl 2 as the activator. We also investigated the effect of the ratio of MgO to ZnCl 2 on the catalyst performance. When the ratio of MgO to ZnCl 2 is 10:0.5, NSLPC-1005 possesses the highest ORR activity with an enormous surface area (1752.54 m2 g−1), abundant active sites, and a hierarchical porous network structure. In alkaline media, NSLPC-1005 has an initial potential of 0.97 V , as well as an excellent half-potential of 0.86 V (vs. Hg/HgO), and an ultimate current density of 5.35 mA cm−2. It exhibits attractive ORR performance as well as outstanding cyclic stability that are comparable to commercial Pt/C electrocatalysts. This research developed an effective approach to synthesize metal-free carbon materials with high activity and long-term durability as electrocatalysts, which have a promising application in sustainable energy conversion technology. [Display omitted] • NSLPC has a 3D flower-like structure facilitating contact of reactants and sites. • NSLPC are constructed of extremely thin carbon nanosheets of only about 10 nm. • Sulfur and nitrogen double doping produce numerous active carbon atoms. • N-doped carbon nanoparticles evenly distributed on NSLPC offering active sites. [ABSTRACT FROM AUTHOR]

Fuel cells are a promising renewable energy technology that depend heavily on noble metal Pt-based catalysts, particularly for the oxygen reduction reaction (ORR). The discovery of new, efficient non-precious metal ORR catalysts is critical for the continued development of cost-effective, high-performance fuel cells. The synthesized carbon material showed excellent electrocatalytic activity for the ORR, with half-wave potential (E 1/2) and limiting current density (JL) of 0.88 V and 5.10 mA·cm−2 in alkaline electrolyte, respectively. The material has a Tafel slope of (65 mV dec−1), which is close to commercial Pt/C catalysts (60 mV dec−1). Moreover, the prepared materials exhibited excellent performance when assembled as cathodes for zinc-air batteries. The power density reached 110.02 mW cm−2 and the theoretical specific capacity was 801.21 mAh g−1, which was higher than that of the Pt/C catalyst (751.19 mAh g−1). In this study, with the assistance of Mg 5 (CO 3) 4 (OH) 2 ·4H 2 O, we introduce an innovative approach to synthesize advanced carbon materials, achieving precise control over the material's structure and properties. This research bridges a crucial gap in material science, with potential applications in renewable energy technologies, particularly in enhancing catalysts for fuel cells. [Display omitted] • The lignin is used as a green carbon precursor. • Synthesis of Fe-CNCs-800 with flower-like hierarchical porosity and interconnected pore structure. • Precise doping of Fe on N was realized to form more Fe-N-C structures to improve ORR activity. [ABSTRACT FROM AUTHOR]

The oxygen reduction reaction (ORR) is an important step in the widespread application of metal-air batteries, so it is necessary to study and develop low-cost and efficient metal-free carbon-based catalysts to catalyze the ORR reaction. Heteroatomic doping, especially N and S co-doped carbon materials, has received much focus as a promising ORR catalyst. Meanwhile, the lignin material has high carbon content, wide source, and low price, and has wide application prospects for the preparation of carbon material catalysts. Here we report a hydrothermal‑carbonation preparation method for the synthesis of carbon microspheres by utilizing lignin derivatives as carbon precursors. And a variety of N, S co-doped carbon microsphere materials were prepared by adding different nitrogen sources (urea, melamine, NH 4 Cl) to the microspheres. The N, S co-doped carbon microspheres (NSCMS-MLSN) catalysts achieved with NH 4 Cl as the nitrogen source displayed superior RR catalytic activity with high half-wave potential (E 1/2 = 0.83 V vs. RHE) and current density (J L = 4.78 mA cm−2). This work provides some references on the method of preparing carbon materials co-doped with N and S and the choice of nitrogen sources. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Hierarchically structured Fe 2 Ni 3 nanoalloy and N-incorporated flower-like carbon matrix. • Synergism between Fe 2 Ni 3 and NFCM essential to achieve first-rate multifunctional performance. • 1.50 V at 10 mA cm−2 and a maintenance up to 76 h for overall water-splitting. • Power density of ∼ 122 mW cm−2 and robust cycling stability for assembled Zn-air battery. • Active species/sites identified through detailed characterizations/comparison studies. A multifunctional electrocatalyst for water splitting and zinc-air battery involves totally-three reactions, namely, oxygen reduction, oxygen evolution, and hydrogen evolution, and is very demanding and challenging. The current study provided an interesting example to achieve such a goal by establishing hierarchical architecture of Fe 2 Ni 3 nanoalloys/N‑incorporated flower-like carbon matrix (Fe 2 Ni 3 -NFCM). The resulting material is free of noble metals and can simultaneously promote the three reactions with excellent activity and robust durability. Significantly, the outstanding parameters ƞ 10 = 280 mV (oxygen evolution), ƞ 10 = 144 mV (hydrogen evolution), and E 1/2 = 0.84 V vs RHE (oxygen reduction) can be accomplished over Fe 2 Ni 3 -NFCM. Moreover, a voltage as low as 1.50 V (10 mA cm−2) and a 76-h durability for water-splitting has been achieved. The assembled Zn-air battery employing the current material as the electrodes can provide the power density being ∼ 122 mW cm−2 plus robust cyclic durability. The multifunctional performance reaches the top level among the various counterparts, the structure-performance correlation has been elucidated and the active species/sites identified through the advanced characterizations and detailed comparison investigations. [ABSTRACT FROM AUTHOR]

Excavating and developing efficient and economical non-metallic nanomaterial catalysts for oxygen reduction reactions (ORR), which are vital for fuel cells, but is still challenging. Here, we synthesize a nitrogen-doped hierarchical porous flower-like carbon nanosheets decorated with nitrogen-doped carbon quantum dots. The hierarchically porosity heteroatom-doped flower-like carbon nanosheets are first synthesized using MgO as hard template, KOH/NaOH as activator, lignin/urea as carbon/heteroatom source, and then lignin-based carbon quantum dots (CQDs) fabricated via microwave hydrothermal are compounded with carbon nanosheets after a one-step hydrothermal treatment. Benefitting from the interconnection of its 3D graphite shell network, abundant active sites, high specific surface area, and multi-scale pore structure, the n-HPFN@CQDs exhibits favorable ORR activity and stability in 0.1 mol KOH media. Compared with commercial Pt/C, the assembled Zn-air batteries using n-HPFN@CQDs as electrode catalysts exhibit comparable discharge performance. This work synthesized a novel and green biomass-based carbon composite materials achieving high-performance for energy conversion applications. [Display omitted] • The n-HPFN@CQDs consists of three-dimensional carbon nanosheets with a hierarchical porous structure. • The influence of the pore structure on the ORR was investigated. • 0-dimensional nitrogen-doped carbon quantum dots as active sites to enhance the electrocatalytic activity of HPFN@CQDs. • The Zn-air batteries prepared with HPFN@CQDs exhibit electrocatalytic performance close to that of commercial Pt/C. [ABSTRACT FROM AUTHOR]

Construction of non-metallic biomass-carbon based catalysts for fuel cell air cathode applications has attracted great attention in recent years. In this work, a convenient and clean technique was developed to fabrication nitrogen-doped lignin-based hierarchical porous lamellar carbon (N-LHPC) via lignin as the carbon precursor, melamine/urea as the nitrogen source and ZnC 2 O 4.2H 2 O as the chemical activator. The N-LHPC has a high specific surface area (491.5 m2 g−1) and macroporous/mesoporous/microporous structures. The nitrogen doping of N-LHPC can reach 16.37 wt%, with a high pyridinic nitrogen content of 41.39 at.%. N-LHPC exhibits a high half-wave potential (0.87 V) and a large limiting current density (5.75 mA cm−2) in 0.1 mol KOH media which is comparable to the commercial Pt/C catalysts. Furthermore, N-LHPC was assembled as air cathode catalyst for Zn-air batteries to evaluate its practical catalytic performance, and the power density was as high as 191 mW cm−2, which was superior to the 20 wt% Pt/C electrocatalyst. This research demonstrates that lignin is a promising carbon source for the fabrication of high catalytic activity and economical electrocatalysts for energy storage systems. [Display omitted] • The lignin is used as a green carbon precursor. • The synthesized N-LHPC has laminated hierarchical porosity with interconnected pore structures. • The prepared N-LHPC has excellent oxygen reduction reaction catalytic performance. • The content of pyridinic nitrogen can reach 41.39 at.% after carbonization. [ABSTRACT FROM AUTHOR]

Construction of non-metallic biomass-carbon based catalysts for fuel cell air cathode applications has attracted great attention in recent years. In this work, a convenient and clean technique was developed to fabrication nitrogen-doped lignin-based hierarchical porous lamellar carbon (N-LHPC) via lignin as the carbon precursor, melamine/urea as the nitrogen source and ZnC 2 O 4.2H 2 O as the chemical activator. The N-LHPC has a high specific surface area (491.5 m2 g−1) and macroporous/mesoporous/microporous structures. The nitrogen doping of N-LHPC can reach 16.37 wt%, with a high pyridinic nitrogen content of 41.39 at.%. N-LHPC exhibits a high half-wave potential (0.87 V) and a large limiting current density (5.75 mA cm−2) in 0.1 mol KOH media which is comparable to the commercial Pt/C catalysts. Furthermore, N-LHPC was assembled as air cathode catalyst for Zn-air batteries to evaluate its practical catalytic performance, and the power density was as high as 191 mW cm−2, which was superior to the 20 wt% Pt/C electrocatalyst. This research demonstrates that lignin is a promising carbon source for the fabrication of high catalytic activity and economical electrocatalysts for energy storage systems. [Display omitted] • The lignin is used as a green carbon precursor. • The synthesized N-LHPC has laminated hierarchical porosity with interconnected pore structures. • The prepared N-LHPC has excellent oxygen reduction reaction catalytic performance. • The content of pyridinic nitrogen can reach 41.39 at.% after carbonization. [ABSTRACT FROM AUTHOR]