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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]

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]

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]

[Display omitted] • A highly efficient molecular SAC has been found whose nitrogen reduction efficiency is comparable to other known SACs. • CrCp and MnBz have extremely low limiting potentials of −0.29 V and −0.37 V, respectively. • In-depth research on the reaction mechanism found that the local magnetic moment plays a key role in the activation of nitrogen. • The descriptor of ΔE(*N 2 H) was discovered, and the mechanism was further investigated. The coordination environment of metal atoms in single-atom catalysts (SACs) has a greater impact on the catalytic performance of electrocatalysts. However, the influence mechanism of interacting ligands on the electrocatalytic nitrogen reduction reaction (NRR) process is still insufficient. Herein, by means of large-scale density functional theory (DFT) computations, the effect of organic ligands on the NRR process is investigated in-depth using half organometallic sandwich molecular SACs, i.e. TMBzs and TMCps (Bz = benzene, Cp = cyclopentadienyl, and TM = transition metal). The results revealed that the NRR performance of all the systems is highly dependent on the choice of d - π interaction within the TM-Ligand complexes. Compared with TMBzs, the TMCps exhibit outstanding NRR activity and significantly suppress HER. Among 16 candidates, CrCp and MnBz are the most promising candidates with an ultra-low limiting potential of −0.29 V and −0.37 V via consecutive mechanism, respectively. Moreover, the systems with higher spin polarizations have better NRR activity. The work provides new insight into the NRR to molecular SACs with different organic ligands. [ABSTRACT FROM AUTHOR]