Caili Zhang

High‐Mo super austenitic stainless steels are prone to precipitate Cr‐ and Mo‐rich σ phases during hot working, which severely impairs their corrosion resistance and mechanical properties. To regulate precipitation, maintain corrosion resistance, and enhance strength, the key lies in rationally controlling the N/Mo ratio. In this study, the precipitation behavior and resultant properties of a conventional S31254 specimen and a specimen with an adjusted N/Mo ratio were comparatively investigated. The results show that in the compositionally modified specimen, the total amount of precipitates during high‐temperature aging is significantly reduced, the precipitates are more dispersed, and the proportion of the Laves phase increases. Moreover, no precipitates are observed even after aging at 1050 °C. This compositional adjustment effectively alleviates the formation of Cr‐depleted zones, and thus significantly improves the intergranular corrosion resistance of the material while simultaneously enhancing its mechanical properties. This study provides valuable insights for the alloy design optimization and performance improvement of super austenitic stainless steels.

Designing low-cost, highly efficient and robust bifunctional electrocatalysts for electrochemical overall water splitting remains a critical and urgent challenge for sustainable hydrogen production. Herein, a hierarchical Fe-modified CoMo sulfur-nitride heterostructure in-situ grown on three-dimensional porous nickel foam (Fe-CoMoNS/NF) is successfully fabricated via a facile two-step hydrothermal in-situ growth and simultaneous sulfurization-nitridation annealing strategy. In alkaline electrolyte, benefiting from the intense interfacial charge redistribution between heterogeneous components, abundant high-valent active sites induced by Fe doping and S,N co-modification, as well as the 3D open hierarchical structure for rapid mass and electron transfer, the as-prepared Fe-CoMoNS/NF only requires ultralow overpotentials of 62.9 mV for hydrogen evolution reaction (HER) and 188.2 mV for oxygen evolution reaction (OER) to achieve a current density of 10 mA cm⁻², respectively. When employed as a bifunctional electrocatalyst for alkaline overall water splitting, the assembled Fe-CoMoNS/NF||Fe-CoMoNS/NF electrolyzer delivers a current density of 10 mA cm⁻² at an ultralow cell voltage of 1.51 V, along with outstanding long-term stability for 100 h without obvious performance attenuation, outperforming most previously reported non-noble metal-based bifunctional electrocatalysts. This work provides a facile and effective strategy to develop high-activity, high-stability non-precious metal-based sulfur-nitrides as advanced bifunctional electrocatalysts for electrochemical overall water splitting.

Designing bifunctional electrocatalysts with high efficiency and low cost for water splitting is a crucial research topic in clean energy technology. In this work, we successfully constructed a hierarchical heterostructure composed of NiFe layered double hydroxide (LDH) and Mo-doped NiCoP supported on nickel foam (NF) through a combined hydrothermal-phosphating-electrodeposition approach. Mo doping induces significant morphological evolution of NiCoP, transforming it into larger and coarser nanowires, while NiFe LDH nanoflowers uniformly decorate the Mo-NiCoP nanowire surfaces to form an integrated heterostructure. Benefited from the constructive collaboration of the NiFe LDH nanoflowers and Mo-NiCoP nanowires hierarchical heterostructure, the NiFe LDH/Mo-NiCoP/NF exhibits outstanding bifunctional activity, requiring only 81 mV for HER and 220 mV for OER to achieve 10 mA cm-2. When employed in overall water splitting, the electrocatalyst demonstrates exceptional durability, maintaining stable operation at 10 mA cm-2 with a low cell voltage of 1.49 V for over 80 hours without degradation. This study presents a sophisticated strategy for the development of efficient phosphide heterostructures composed of non-noble metals, serving as bifunctional electrocatalysts for comprehensive alkaline water splitting.

Designing bifunctional electrocatalysts with high efficiency and low cost for water splitting is a crucial research topic in clean energy technology. In this work, we successfully constructed a hierarchical heterostructure composed of NiFe layered double hydroxide (LDH) and Mo-doped NiCoP supported on nickel foam (NF) through a combined hydrothermal-phosphating-electrodeposition approach. Mo doping induces significant morphological evolution of NiCoP, transforming it into larger and coarser nanowires, while NiFe LDH nanoflowers uniformly decorate the Mo-NiCoP nanowire surfaces to form an integrated heterostructure. Benefited from the constructive collaboration of the NiFe LDH nanoflowers and Mo-NiCoP nanowires hierarchical heterostructure, the NiFe LDH/Mo-NiCoP/NF exhibits outstanding bifunctional activity, requiring only 81 mV for HER and 220 mV for OER to achieve 10 mA cm-2. When employed in overall water splitting, the electrocatalyst demonstrates exceptional durability, maintaining stable operation at 10 mA cm-2 with a low cell voltage of 1.49 V for over 80 hours without degradation. This study presents a sophisticated strategy for the development of efficient phosphide heterostructures composed of non-noble metals, serving as bifunctional electrocatalysts for comprehensive alkaline water splitting.

The photocatalytic conversion of ethanol and the simultaneous development of hydrogen technology play a role in solving the energy crisis and reducing environmental pollution. In this research, rod-like M-MoS₂ serves as a channel for charge transfer, leading to superior photocatalytic activity compared to H-MoS₂. Further, two-dimensional (2D) B-doped C₃N₄ (BCN) nanosheets were anchored on the one-dimensional (1D) rod-like M-MoS₂ surface to form a 1D/2D heterojunction, with M-MoS₂/BCN-0.08 (mass ratio of M-MoS₂:BCN of 0.08:1) exhibiting the highest photocatalytic performance. Under visible light irradiation, the ethanol conversion rate reached 1.79% after 5 h of photocatalytic reaction per gram of catalyst, while generating 421 μmol of 2,3-butanediol (2,3-BDO), 5460 μmol of acetaldehyde (AA), and 5410 μmol of hydrogen gas (H₂). This different characterization provides evidence that a significant amount of photoinduced electrons generated in BCN under illumination conditions rapidly transfer to the conduction band (CB) of M-MoS₂ through the rod-like structure of M-MoS₂, and finally transfer to Pt to promote the production of hydrogen gas. The photoinduced holes in the valence band (VB) of M-MoS₂ are rapidly consumed by ethanol upon transferring to BCN, effectively separating the photoinduced electron–hole pairs and resulting in superior photocatalytic performance.

S is a common corrosion medium for austenitic stainless steels. The severe intergranular fracture of austenitic stainless steels occurs in sulfur environments. In this paper, the permeation of S at different atomic positions for three symmetric tilt grain boundary types, i.e., Σ5(210), Σ5(310), and Σ9(114) have been computed using first-principles calculations. S has the strongest segregation tendency in the Σ5(210) grain boundary. A high content of S at the grain boundary indicates harm to the grain boundary. Sulfur segregation in the grain boundaries can weaken the strength of the metallic bond. When Mo and Cr are present at the Σ5(210) grain boundary, the sulfur-induced embrittlement is inhibited. With increased S concentration at the grain boundary, the coexistence of Mo and Cr can suppress the intergranular fracture of S on the grain boundary. The reason why high-Mo stainless steel has excellent sulfur-induced intergranular corrosion resistance is explained at the atomic level.

Graphene has attained a considerable amount of popularity as an attractive ultra‐thin reinforcement for nickel (Ni) matrix composites in recent years. However, its excellent reinforcement efficiency is suffered from the agglomeration of graphene nanosheets in manufacturing process and the poor bonding strength of graphene with Ni matrix. To overcome these two problems, one of the efficient strategies is to in‐situ grow graphene reinforcements on Ni particles for powder metallurgy. This work aims to synthesize uniform graphene@Ni composite particles by using polymethyl methacrylate (PMMA) as the solid sources for chemical vapor deposition (CVD) process. The results demonstrate that few‐layer or multilayer graphene with different morphologies can be grown on the particles by controlling the PMMA content and annealed temperature, respectively. The optimum condition for the formation of high‐quality few‐layer graphene is 1.0 mg·ml ⁻¹ PMMA and 900 °C. A competition mechanism rises from the growth kinetic, and the spatial confinement effect has led to the formation of graphene with different microstructures and morphologies.

The addition of B can inhibit the precipitation of σ phases at the grain boundary to improve the hot workability and corrosion resistance for super austenitic stainless steel with high Cr and Mo content. This study focused on the interaction between B and Mo at the Fe–Cr(111)/Cr₂O₃(0001) interface and its effect on interfacial adhesion by employing the first-principles method, especially the effect of B on the segregation behavior of Mo. The most stable O-terminated Fe/Cr₂O₃ interface was chosen as the basic configuration. The segregation energy and the work of separation were calculated for the metal/chromia interface with Fe–Cr as the substrate. It has been demonstrated that B can promote the diffusion of Mo atoms into the oxide layer to increase the content of Mo in the passive film. In addition, the interfacial adhesion is higher at the most segregated sites. However, it is more difficult for two or more Mo atoms than a single Mo atom to diffuse into the oxide part with the effect of B, indicating that B can only improve the Mo content of the passive film to a small extent. The electronic properties were also further discussed to analyze the interactions and the binding characters between doped atoms and their surrounding atoms and to explain the underlying reasons for the variation of interfacial adhesion.