Single atom catalysts (SACs) have attracted great attention, yet the quest for highly-efficient catalysts is driven by the current obstacles of ambiguous structure-performance relationship. Here, we report a nature keratin-based Fe-S₁N₃ SACs with ultrathin two-dimensional (2D) porous carbon nanosheets structure, by controlling the active center through the precise coordination of sulfur and nitrogen. Compared with natural silk-based Fe-N₄ catalyst, the Fe-S₁N₃ SACs exhibit excellent Fenton-like oxidation degradation ability. X-ray absorption fine structure (XAFS) and electron paramagnetic resonance (EPR) results confirm that S doping is conducive to electron transfer, to accurately generate·OH with high oxidative degradation capacity at the active site. Therefore, the optimized Fe-S₁N₃ catalyst showed higher oxidation degradation activity for organic pollutant substrates (methylene blue (MB), Rhodamine B (RhB) and phenol), significantly superior to Fe-N₄ samples. This work is devoted to the treatment and application of natural fibers, which provides a novel method for the synthesis of SACs and the regulation of atomic coordination environment.

Designing catalysts with highly active, selectivity, and stability for electrocatalytic CO₂ to formate is currently a severe challenge. Herein, we developed an electronic structure engineering on carbon nano frameworks embedded with nitrogen and sulfur asymmetrically dual-coordinated indium active sites toward the efficient electrocatalytic CO₂ reduction reaction. As expected, atomically dispersed In-based catalysts with In-S₁N₃ atomic interface with asymmetrically coordinated exhibited high efficiency for CO₂ reduction reaction (CO₂RR) to formate. It achieved a maximum Faradaic efficiency (FE) of 94.3% towards formate generation at −0.8 V vs. reversible hydrogen electrode (RHE), outperforming that of catalysts with In-S₂N₂ and In-N₄ atomic interface. And at a potential of −1.10 V vs. RHE, In-S₁N₃ achieves an impressive Faradaic efficiency of 93.7% in flow cell. The catalytic performance of In-S₁N₃ sites was confirmed to be enhanced through in-situ X-ray absorption near-edge structure (XANES) measurements under electrochemical conditions. Our discovery provides the guidance for performance regulation of main group metal catalysts toward CO₂RR at atomic scale.

Tandem catalysis, capable of decoupling individual steps, provides a feasible way to build a high-efficiency CO₂ electroconversion system for multicarbons (C₂₊). The construction of electrocatalytic materials is one of focusing issues. Herein, we fabricated a single atom involved multivalent oxide-derived Cu composite material and found it inclined to reconstruct into oxygen-deficient multiphase Cu based species hybridized with monatomic Ni on N doped C matrix. In this prototype, rapid CO generation and C–C coupling are successively achieved on NiN₄ sites and surface amorphized Cu species with defects, resembling a micro-production line. In this way, the in situ formed tandem catalyst exhibited a high Faradaic efficiency (FE) of ∼ 78% for C₂₊ products along with satisfactory durability over 50 h. Particularly, the reconstruction-induced amorphous layer with abundant asymmetric sites should be favorable to improve the ethanol selectivity (FE: 63%), which is about 10 times higher than that of the non-tandem Cu-based contrast material. This work offers a new approach for manipulating tandem catalyst systems towards enhancing C₂₊ products.

NiFe (oxy)hydroxide has been widely used as a benchmark anodic catalyst for oxygen evolution reactions (OERs) in alkaline water electrolysis devices; however, the energy saving actually takes contributions from both the anodic OER and cathodic hydrogen evolution reaction (HER). In this work, we observe the catalytic promotion upon the in situ-derived NiFe (oxy)hydroxide from the NiFe alloy monolithic electrode and also point out that the coupled nickel cathode is contaminated, leading to the loss of HER activity and a reduction in overall efficiency. It is found that Ni²⁺ and Fe³⁺ cations are inevitably detached from the anode into the electrolyte and electrodeposited on the nickel cathode after the three-month industrial simulation. This research presents the significant enhancement of the oxygen evolution catalysis using an in situ aging process and emphasizes that the catalytic application should not only be isolated on the half reaction, but a reasonable coupled electrode match to get rid of the contamination from the electrolyte is also of great significance to sufficiently present the intrinsic catalytic yielding for the real application.

The catalyst is the pivotal component in CO₂ electroreduction systems for converting CO₂ into valuable products. Carbon-based single-atom materials (CSAMs) have emerged as promising catalyst candidates due to their low cost and high atomic utilization efficiency. The rational design of the morphology and microstructure of such materials is desirable but poses a challenge. Here, we employed different Mg(OH)₂ templates to guide the fabrication of two kinds of amorphous nitrogen-doped carbon nanosheet-supported Fe single atoms (FeSNC) with rough and flat surface structures. In comparison to flat FeSNC with saturated FeN₄ sites, the rough FeSNC (R-FeSNC) exhibited unsaturated FeN_4−x sites and contracted Fe-N bond length. The featured structure endowed R-FeSNC with superior capacity of catalyzing CO₂ reduction reaction, achieving an exceptional CO selectivity with Faradaic efficiency of 93% at a potential of −0.66 V vs. RHE. This study offers valuable insights into the design of CSAMs and provides a perspective for gaining a deeper understanding of their activity origins.

This study integrates geostatistical analysis, correlation analysis and pollution load assessment to investigate the spatial distribution characteristics and environmental impacts of rural domestic pollution emissions in the Yellow River Basin, laying a foundation for the sustainable development of rural areas and zoned and classified management of rural domestic sewage in the basin. Results show that: ① The average rural domestic sewage discharge coefficient in the basin is 25.67 L/(person·day), and the average pollutant generation coefficients are as follows: chemical oxygen demand (COD) 23.08 g/(person·day), ammonia nitrogen (NH₃-N) 0.71 g/(person·day), total nitrogen (TN) 1.29 g/(person·day) and total phosphorus (TP) 0.11 g/(person·day); ② Rural sewage discharge coefficients near urban areas are higher than other rural areas in the same jurisdiction, with downstream areas significantly exceeding upstream non-urban areas; ③ Youth population, illiterate population, average education years and annual precipitation are key influencing factors, showing significant negative correlations with the former two and positive correlations with the latter two; ④ The maximum equivalent load contribution of rural domestic pollution to the water quality objectives of the Yellow River’s main streams and tributaries is merely 2.01%. Overall, rural per capita domestic sewage discharge in the basin is at a low level with obvious regional differences, mainly correlated with demographic, educational and climatic factors, and its impact on the basin’s water quality objectives is negligible.