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A facile and eco‐friendly strategy is presented for synthesizing novel nanocomposites, with MoP quantum dots (QDs) as cores and graphitic carbon as shells, these nanoparticles are dispersed in a nitrogen and phosphorus‐doped porous carbon and carbon nanotubes (CNTs) substrates (MoP@NPC/CNT). The synthesis involves self‐assembling reactions to form single‐source precursors (SSPs), followed by pyrolysis at 900 °C in an inert atmosphere to obtain MoP@NPC/CNT‐900. The presence of carbon layers on the MoP QDs effectively prevents particle aggregation, enhancing the utilization of active MoP species. The optimized sample, MoP@NPC/CNT‐900, exhibits remarkable electrocatalytic activity and durability for the hydrogen evolution reaction (HER). It demonstrates a low overpotential of 155 mV at 10 mA cm−2, a small Tafel slope of 76 mV dec−1, and sustained performance over 20 hours in 0.5 M H2SO4. Furthermore, the catalyst shows excellent activity in 1 M KOH, with a relatively low overpotential of 131 mV and long‐term durability under constant current input. The exceptional HER activity can be attributed to several factors: the superior performance of MoP QDs, the large surface area and good conductivity of the carbon substrates, and the synergistic effect between MoP and carbon species. [ABSTRACT FROM AUTHOR]

Water‐splitting processes require advanced catalysts for the electrocatalytic hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). A facile and cost‐effective approach using single‐source precursors (SSPs) to prepare active and durable bifunctional electrocatalysts consisting of core–shell structured transition metal phosphide (TMPs) nanoparticles dispersed and immobilized in a highly defective N‐, P‐codoped carbon matrix. The bimetallic FeNi phosphide supported on N‐, P‐codoped carbon is synthesized through pyrolysis at 900 °C under an argon atmosphere (FeNiP@NPC‐900), displaying promising electrocatalytic performance for both HER and OER, with low overpotentials of 191 and 278 mV, respectively. Furthermore, FeNiP@NPC‐900 exhibits remarkable durability in both acidic and alkaline electrolytes. The excellent catalytic and long‐term performance is attributed to several factors, including the novel SSP approach, which prevents the agglomeration of active TMPs particles, the in situ formation of exposed nanopores during the carbonization of the precursor without using surfactants, and the heterostructure between highly defective carbon and TMPs, which positively influences the electronic structure at the interface and facilitates charge transfer. The unique core–shell nanostructure protects the catalytically active phase from corrosion and synergistically promotes the activity performance. Therefore, a new strategy for designing active and stable heterostructured TMPs@carbon‐based electrocatalysts is provided. [ABSTRACT FROM AUTHOR]

Carbon supported metallic nanomaterials are of great interest due to their low‐cost, high durability and promising functional performance. Herein, a highly active oxygen evolution reaction (OER) electrocatalyst comprised of defective carbon shell encapsulated metal (Fe, Co, Ni) nanoparticles and their alloys supported on in‐situ formed N‐doped graphene/carbon nanotube hybrid is synthesized from novel single‐source‐precursors (SSP). The precursors are synthesized by a facile one‐pot reaction of tannic acid with polyethylenimine and different metal ions and subsequent pyrolysis of the SSP. Benefiting from the heteroatom doping of carbon and formation of well‐encapsulated metal/alloy nanoparticles, the obtained FeNi@NC‐900 catalyst possesses lowest overpotentials of 310 mV to achieve a current density of 10 mA cm−2 for OER with a small Tafel slope value of 45 mV dec−1, indicating excellent catalytic performance due to the following features: (1) A synergistic electronic effect among metal alloy nanoparticles, nitrogen‐doped carbon, and entangled carbon nanotubes; (2) penetration of electrolyte is promoted towards the active sites through the porous structure of the formed mesoporous carbon clusters; (3) the unique core‐shell nanostructure of the hybrid material effectively curbs the degradation of electrocatalyst by protecting the alloy nanoparticles from harsh electrolyte. This work advances an inexpensive and facile method towards the development of transition metal‐based hybrid material for potential energy storage and conversion. [ABSTRACT FROM AUTHOR]

In the present work, bulk Si3N4/HfBxN1‐x ceramic nanocomposites were successfully fabricated via a polymer‐derived ceramic approach. The chemical reaction to form the single‐source precursor was confirmed by FT‐IR and XPS, in which both Si−H and N−H groups of perhydropolysilazane react with borane dimethyl sulfide complex and tetrakis(dimethylamido) hafnium(IV). The investigation of the polymer‐to‐ceramic transformation of the synthesized precursors indicates that Hf‐ and B‐modified PHPS exhibits high ceramic yields of up to 100 wt % after pyrolysis at 1000 °C under ammonia. Moreover, XRD and TEM results show that the SiHfBN ceramics with a molar ratio of B : Hf=5 and 10 resist crystallization at temperatures up to 1500 °C and separate after annealing at 1700 °C into nanocomposites comprising of an α‐Si3N4 matrix with embedded ternary HfBxN1‐x phases, solid solutions of rock salt‐type HfN and HfB. Based on the investigation, warm‐pressing was applied to fabricate bulk SiHfBN specimens, and the oxidation behavior of samples annealed at 1700 °C was recorded at 1500 °C over a range of oxidation times between 1 and 50 h. The weight changes of Si3N4/HfBxN1‐x ceramics with B : Hf molar ratios of 2 : 1, 5 : 1 and 10 : 1 are 4.31 %, 4.37 % and 2.57 %, respectively. The formation of HfSiO4, B2O3 and SiO2 during oxidation plays a crucial role for the improvement of the oxidation resistance of the Si3N4/HfBxN1‐x ceramics. [ABSTRACT FROM AUTHOR]

Owing to the versatility in their chemical and physical properties, transition metal perovskite oxides have emerged as a new category of highly efficient photocatalysts for photoelectrochemical (PEC) water splitting. Here, to understand the underlying mechanism for the enhanced PEC water splitting in mixed perovskites, ideal epitaxial thin films of the BiFeO3–SrTiO3 system are explored. The electronic structure and carrier dynamics are determined from both experiment and density‐functional theory calculations. The intrinsic phenomena are measured in this ideal system, contrasting to commonly studied polycrystalline solid solutions where extrinsic structural features obscure the intrinsic phenomena. It is determined that when SrTiO3 is added to BiFeO3 the conduction band minimum position is raised and an exponential tail of trap states from hybridized Ti 3d and Fe 3d orbitals emerges near the conduction band edge. The presence of these trap states strongly suppresses the fast electron–hole recombination and improves the photocurrent density in the visible‐light region, up to 16× at 0 VRHE compared to the pure end member compositions. This work provides a new design approach for optimizing the PEC performance in mixed perovksite oxides. Epitaxial BiFeO3–SrTiO3 thin films are investigated in order to understand the correlation between electronic structure and carrier dynamics in perovskite solid solution photoelectrodes. As well as shifting the conduction band edge up, an exponential tail of trap states emerges near the conduction band edge which suppresses the fast recombination of electrons and holes and strongly enhances the photocurrent density. [ABSTRACT FROM AUTHOR]