Artificial humic acid regulates the impact of fungal community on soil macroaggregates formation.

Artificial humic acid (A-HA), which is synthesized from agricultural wastes and has high similarity to a natural humic substance (HS) extracted from soil, has been proven by our group to have potential for biological carbon sequestration in black soils. However, the mechanism involves in the application of A-HA on soil aggregation processes resulting from microbial activity stimulation and modifications to microbial communities remains unclear. This study investigates the correlation between the formation and stability of soil aggregates and fungal communities with various amounts of A-HA added to the rhizosphere and non-rhizosphere soil. A-HA can increase the total organic carbon (TOC) and dissolved organic carbon (DOC) concentrations in soil, promoting macroaggregate formation and increasing the mean weight diameter (MWD). In addition, soil aggregate binding agents such as polysaccharides, protein, extracellular polymeric substances (EPS), and glomalin-related soil protein (GRSP) are significantly increased by the addition of A-HA. A-HA can drive microaggregate to assemble into macroaggregate by increasing the abundance of beneficial fungi (e.g., Trichoderma and Mortierella). The co-occurrence network supports that A-HA shifted the key species and increased interactions of fungal taxa. This study will lay a solid foundation for sustainable agricultural development of A-HA application for soil fertility restoration in the future.

Solvent-assisted assembly of reduced graphene oxide/MXene-polypyrrole composite film for flexible supercapacitors.

Two-dimensional (2D) materials represented by graphene and MXene have attracted extensive attention in the field of energy storage. However, the automatic stacking and poor stability of 2D materials considerably limit their electrochemical performance. In this article, we apply a design strategy based on combining the ternary components of reduced graphene oxide (rGO), MXene, and polypyrrole (PPy) into one electrode to form a flexible film with a sandwich structure. As a result, the resulting rGO/MXene-PPy composite electrode inherits the characteristics of high conductivity, robust mechanical properties, and pseudocapacitance. In addition to providing capacitive contributions, the PPy serves as a blocker to prevent face-to-face restacking of the 2D nanosheets and also as a coating layer to significantly protect MXene from oxidation. Consequently, the rGO/MXene-PPy electrode exhibits a high specific capacitance of 408.2 F g-1 and a superior rate performance, with 67.3% capacitance retention at an increased current density of 10.0 A g-1. Furthermore, the as-assembled asymmetric supercapacitor possesses a pronounced energy density of 11.3 Wh kg-1 (35.5 Wh L-1) at a power density of 500.0 W kg-1 (1570.0 W L-1) and remarkable cycling stability, with 8.8% capacitance deterioration after 10,000 cycles. This work demonstrates the potential for application of as-prepared rGO/MXene-PPy electrodes in flexible energy storage devices with high volumetric/gravimetric energy and power densities.