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Photoelectrochemical hydrogen production technology holds promise for directly and swiftly generating green hydrogen, which is pivotal for human welfare; however, it faces challenges posed by the energetically sluggish oxygen evolution reaction (OER). Cobalt-based nitrides are considered excellent photoelectrochemically active in the OER (PEOER) catalysts, and their conductivity and photoconversion efficiency remain relatively low. This paper presents the fabrication of Ni-alloyed Co4N nanowire arrays on carbon cloth ((Co1–xNix)4N NWAs/CC) as PEOER catalysts. By analyzing advanced in situ Raman and X-ray photoelectron spectroscopy (XPS) results, we discovered that Ni not only enhances the conductivity of the catalyst but, more importantly, also creates more photoexcited Co2+ OER centers and favors its reconstruction to CoOOH to charge PEOER. Furthermore, nitrogen plays a critical role in transforming pyridinic nitrogen into other forms of nitrogen to stabilize the catalyst's structure. These advantages endow (Co0.74Ni0.26)4N NWAs/CC with remarkable PEOER enhancement (988%), which drives the standard current density of 10 mA cm–2 with only a 283 mV overpotential along with good durability. This research provides insights into the PEOER mechanisms of cobalt-based transition metal nitrides, providing a way for designing next-generation PEOER catalysts. [ABSTRACT FROM AUTHOR]

Reducing electrolyte usage constitutes the prerequisite to construct high-energy-density lithium–sulfur (Li–S) batteries. However, the cathode kinetics is severely blocked under lean-electrolyte conditions. Electrocatalysts have been widely employed to boost the cathode kinetics, yet their effectiveness under lean-electrolyte conditions remains unclear. Herein, the cathode kinetics promotion effectiveness of electrocatalysts is systematically evaluated in lean-electrolyte Li–S batteries. The kinetics promotion effects on both liquid–liquid and liquid–solid conversions are more prominent at higher sulfur concentrations using a titanium nitride (TiN) electrocatalyst. Similarly, the discharge capacity increment and cell polarization decrease afforded by the TiN electrocatalyst are more significant in lean-electrolyte Li–S batteries than in flooded-electrolyte ones. Polarization decoupling analysis further identifies activation polarization as the main challenge under lean-electrolyte conditions, which can be effectively overcome by the TiN electrocatalyst. Moreover, the energy density of 2 Ah Li–S pouch cells increases by 19% using the TiN electrocatalyst. This work elucidates that electrocatalysts are more effective in lean-electrolyte Li–S batteries and highlights advanced electrocatalyst design for high-energy-density Li–S batteries. [ABSTRACT FROM AUTHOR]

Solar irradiation can efficiently promote the kinetics of the oxygen evolution reaction (OER) during water splitting, where heterojunction catalysts exhibit excellent photoresponsive properties. However, insights into the origins of photoassisted OER catalysis remain unclear, especially the interfaced promotion under convergent solar irradiation (CSI). Herein, novel allotropic Co5.47N/CoN heterojunctions were synthesized, and corresponding OER mechanisms under CSI were comprehensively uncovered from physical and chemical aspects using the in situ Raman technique and electrochemical cyclic voltammetry method. Our results provide a unique mechanism where high‐energy UV light promotes the Co3+/4+ conversion process in addition to the ordinary photoelectric effect excitation of the Co2+ material. Importantly, visible light under CSI can produce a photothermal effect for Co2+ excitation and Co3+/4+ conversion, which promotes the OER significantly more than the usual photoelectric effect. As a result, Co5.47N/CoN (containing 28% CoN) obtained 317.9% OER enhancement, which provides a pathway for constructing excellent OER catalysts. [ABSTRACT FROM AUTHOR]

People's increasing demand for fossil fuels not only leads to environmental pollution but also highlights their non-renewable nature. Therefore, the urgency of developing renewable energy sources is evident. Tree branches and leaves undergo cycles of growth and decay with the changing seasons, showcasing their renewable potential. Despite this, they remain underutilized as new energy materials, particularly in the realm of high-energy-density lithium batteries. While this paper did not directly explore the utilization of various branches and leaves as raw materials for lithium–sulfur battery (LSB) cathodes, it revealed promising findings: they not only demonstrate good battery capacity but also boast considerable cycle life. The carbonized material from the leaves of Acer buergerianum can be used as the electrode of LSBs and could achieve 318.8 mA h g−1 at 4C and a decay rate of only 0.03% at 1C for 400 cycles., respectively. Therefore, the innovative method of turning decaying leaves into energy contributes significantly to the future of renewable energy and environmental protection. [ABSTRACT FROM AUTHOR]

Rechargeable Li–S batteries (LSBs) are emerging as an important alternative to lithium‐ion batteries (LIBs), owing to their high energy densities and low cost; yet sluggish redox kinetics of LiPSs results in inferior cycle life. Herein, we prepared multifunctional self‐supporting hyphae carbon nanobelt (HCNB) as hosts by carbonization of hyphae balls of Rhizopus, which could increase the S loading of the cathode without sacrificing reaction kinetics. Trace platinum (Pt) nanoparticles were introduced into HCNBs (PtHCNBs) by ion‐beam sputtering deposition. Based on the X‐ray photoelectron spectroscopy analyses, the introduced trace Pt regulated the local electronic states of heteroatoms in HCNBs. Electrochemical kinetics investigation combined with operando Raman measurements revealed the accelerated reaction mechanics of sulfur species. Benefiting from the synergistic catalytic effect and the unique structures, the as‐prepared PtHCNB/MWNCT/S cathodes delivered a stable capacity retention of 77% for 400 cycles at 0.5 C with a sulfur loading of 4.6 mg cm−2. More importantly, remarkable cycling performance was achieved with an high areal S loading of 7.6 mg cm−2. This finding offers a new strategy to prolong the cycle life of LSBs. [ABSTRACT FROM AUTHOR]

Hollow structures with a hierarchical architecture and multi-composition have attracted extensive interest because of their fascinating physicochemical properties as well as wide applications. To improve the efficiency of overall water splitting, highly active and stable electrocatalysts are highly desirable. A novel high-efficiency oxygen defect based hierarchical hollow nanosheet-based-nanosphere Co–NiMoO4-HNS electrocatalyst for oxygen evolution was arranged by doping Co on a Ni-MoEG yolk/shell nanosphere. Co–NiMoO4-HNS has a greater hydrophilicity and smaller band gap than that of NiMoO4-CS. Post OER characterization indicates that the main active phase of the Co2–NiMoO4-HNS catalysts toward the OER are amorphous Ni3+, Co3+, and H–O and the high-valent Mo (+6) can make nickel and cobalt better maintain Ni3+ and Co3+ sites. Remarkably, this hierarchical hollow Co2–NiMoO4-HNS catalyst exhibits a favorable catalytic performance toward the oxygen evolution reaction (OER) with a receivable overpotential of 270 mV achieving a current density of 10 mA cm−2 and a Tafel slope of 65 mV dec−1. In expansion, as an electrocatalyst, Co2–NiMo4-HNS appeared to have a great long-term steadiness in the electrolyte. This work may give a broad hypothetical and specialized background for plans of cost-effective bifunctional electrocatalysts. [ABSTRACT FROM AUTHOR]