ABSTRACT Reducing the friction‐induced material loss while maintaining the functional response of shape‐memory alloy (SMA) coatings was essential for the resource‐efficient and durable high‐temperature service. In this study, Cr 2 O 3 ‐reinforced CuAlMnTi SMA coatings were fabricated by laser direct energy deposition (LDED), and the composition‐dependent relationships among the microstructural evolution, phase transformation and the high‐temperature tribological performance were systematically investigated. The results show that the introduction of Cr 2 O 3 particles promotes the grain refinement and regulates the phase constitution and transformation behavior of CuAlMnTi SMA matrix, increasing the coating hardness by 9%–44% relative to the substrate. The average coefficients of friction (COFs) and wear rates are decreased with the increase of Cr 2 O 3 content, and the minimal COF and wear rate reach 0.533 and 71.1 ± 3.6 μm 3 ·N −1 ·mm −1 , respectively, demonstrating the friction reduction and wear resistance. The dominant wear mechanisms include adhesive wear, abrasive wear and oxidative wear, which are suppressed by the uniformly distributed Cr 2 O 3 particles and protective oxide films. These findings establish the mechanistic relationship among the Cr 2 O 3 reinforcement, phase transformation and tribological response, providing the viable strategy for the resource‐efficient wear protection and extending the service of SMA‐coated smart structural components. image
ABSTRACT This study presents a sustainable direct current triboelectric nanogenerator fabricated from PEDOT:PSS‐coated Xuan paper using a traditional calligraphy brush method. The combination of Xuan paper, a biodegradable, renewable, and culturally significant material, with a traditional brush‐based fabrication method provides a sustainable strategy for energy harvesting applications. The water based PEDOT:PSS/PVA/pullulan conductive ink allows gentle and uniform coating, while the soft bristles of the brush enable deep penetration into the cellulose fiber network, forming a smooth, continuous, and flexible conductive layer. The resulting Al/PEDOT:PSS interface exhibits a built in potential difference of approximately 0.9 eV, enabling efficient charge transfer and rectified direct current generation. The device achieves an open circuit voltage (Voc) of about 0.75 V, a short circuit current (Isc) of 300 μA, and a maximum power density of 41.4 μW cm−2 under a 2 N mechanical load. It also demonstrates stable electrical outputs under various human motions such as finger tapping, elbow bending, and heel pressing. This work establishes a novel and eco‐friendly strategy that merges traditional art techniques with sustainable material science, advancing biodegradable and self‐powered energy harvesting systems.
ABSTRACT Electrochemical nitrogen reduction reaction (NRR) offers a promising route for ammonia synthesis under ambient conditions, but its efficiency is severely limited by the competing hydrogen evolution reaction. Computational screening commonly assesses NRR–HER selectivity from the initial adsorption preference between *N2 and *H. However, this static descriptor does not establish whether an N2‐covered catalyst will subsequently favor N2 hydrogenation over neighboring‐site H adsorption. Here, using homonuclear transition‐metal dimers anchored on C2N as model dual‐atom catalysts, we examine this competition through a hybrid explicit/implicit solvation model and pathway‐resolved kinetic analysis. Solvation alters the stability of key *NNH intermediates and narrows the set of kinetically viable candidates. The remaining catalysts exhibit distinct competition between direct *N2 hydrogenation and Volmer‐type H adsorption, with applied potential further modifying the accessibility of both pathways. These results demonstrate that favorable initial *N2 adsorption alone is insufficient to predict sustained NRR selectivity. Instead, solvated first‐hydrogenation kinetics and potential‐dependent pathway branching provide a more rigorous mechanistic framework for evaluating NRR–HER competition on dual‐site catalysts.
ABSTRACT The concurrent crises of plastic pollution, climate change, and resource scarcity demand innovative biotechnological solutions. This review explores an emerging paradigm to produce polyhydroxyalkanoate (PHA) bioplastics using wastewater sludge (WWS) as a primary feedstock. WWS is a complex yet globally abundant waste stream rich in organic carbon and nutrients, making it a promising and cost‐effective substrate for sustainable PHA production. We discuss metabolic engineering strategies designed to transform mixed microbial cultures into robust and well‐characterized industrial PHA producers, including the heterologous expression of key PHA biosynthesis genes such as phaCAB. Direct PHA synthesis on sludge‐derived media is a promising, integrated approach to waste management and sustainable production, transforming WWS from a treatment‐focused service into a resource‐recovery as bioplastics. This review critically evaluates the key challenges associated with this strategy, including process scalability, optimization of PHA yield, downstream processing, sustainability, and integration within circular bio‐systems. Conventional WWS management emits ~0.3–1.5 kg CO2‐eq/kg PHA dry sludge, whereas life cycle assessments (LCAs) framework indicates that PHA production from WWS results in emissions of approximately ~1.5–3.5 kg CO2‐eq/kg PHA produced. Compared with ~3.5–6.5 kg CO2‐eq/kg PHA fossil‐based plastic replaced on a cradle‐to‐grave basis. When avoided WWS disposal and fossil plastic substitution are considered, WWS‐derived PHAs production has the potential to deliver net climate benefits within a circular‐economy framework.
Electrochemical and photoelectrochemical hydrogen production are often pursued separately, even though both ultimately require electron consumption at the catalyst-electrolyte interface to form H2. Integrating light harvesting, charge transport, and catalysis within a single photoelectrode can impose intrinsic trade-offs. Here, we propose a charge-decoupled electrode architecture that enables dual-mode electrochemical and photoelectrochemical hydrogen production by separating charge generation from charge consumption within one platform. Vertically aligned n-type GaN nanorods grown on silicon provide an electrically continuous pathway for charge transport and, under illumination, a source of photocarriers, while a continuous two-dimensional TiS2 layer functions as an efficient interfacial charge transfer layer and the hydrogen-evolution-active interface. In electrochemical operation, externally supplied electrons are delivered through n-GaN and consumed at the TiS2 surface to produce hydrogen at the working electrode. Under photoelectrochemical operation, photocarriers generated in n-GaN are separated at the TiS2/n-GaN junction, and the electrode operates in photocathodic mode to drive proton reduction and hydrogen production at the illuminated working-electrode surface. These results demonstrate charge-decoupled functional switching and highlight its potential as an electrode-architecture principle for carbon-neutral hydrogen production across electrochemical and photoelectrochemical regimes.image
