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Developing seawater‐based high‐performance oxygen reduction reaction (ORR) electrocatalysts is meaningful to renewable energy storage and conversion, and the Fe‐based derivatives encapsulated by nitrogen (N) doped carbon are the typical representative. Nevertheless, unrevealing the mechanism of N configuration to ORR activity and chlorine resistance is still a great challenge. In this work, a feasible strategy is developed to prepare controllable pyridinic/pyrrolic‐N doped carbon‐coated Fe‐based electrocatalysts (FexN‐NC). Drawing support from the H3PO4 blocking based in situ Fourier transform infrared spectroscopy (FTIR) test and density‐functional theory (DFT) calculation, the tandem effect of pyridinic‐N and pyrrolic‐N on ORR is proved. Additionally, the low hydrogen peroxide (H2O2) yield and 4e− pathway of FexN‐NC demonstrate that N doping effectively reduces the adsorption of Cl−, which is consistent with the low Cl− adsorption energy of DFT. The half‐wave potential (E1/2) of FexN‐NC for ORR reaches 0.874 V in alkaline seawater, and ZABs assembled with FexN‐NC as the air cathode deliver a remarkable power density (162 mW cm−2), along with excellent long‐term durability (>400 h). [ABSTRACT FROM AUTHOR]

The development of an electrocatalyst for oxygen reduction reaction (ORR) in a seawater electrolyte is the key to realizing the utilization of marine resources and application of Zn–air batteries (ZABs). Exploring the adsorption and desorption behavior of oxygen can guide the design of catalysts fundamentally and improve the catalytic performance. On this basis, WC and Co on nitrogen‐doped carbon (WC‐Co@NC) with an interfacial built‐in electric field (BEF) is designed as an ORR catalyst. The theoretical calculation certifies that the BEF of W─C─Co connections promote charge separation and directional migration, thus realizing the oxygen adsorption equilibrium and speeding up the process of ORR. These give WC‐Co@NC a high half‐wave potential of 0.872 V, and the alkaline seawater‐based ZAB with WC‐Co@NC as the air cathode has a peak power density of 188.8 mW cm−2 and excellent stability. This work can provide a basis for the rational design of the cathode of alkaline seawater‐based ZAB, and can also give a new direction for the utilization of seawater resources. [ABSTRACT FROM AUTHOR]

Exploring Ru-based materials with strong metal-support interaction (SMSI) is a promising method to develop superb activity and long-term durability electrocatalysts for hydrogen evolution reaction (HER). Herein, a heterojunction substrates strategy is proposed to stimulate the intrinsic activity of Ru nanoparticles loading on FeTeO (Ru/FeTeO) by activating the strong metal-heterojunction substrate interaction (SMHSI). Density functional theory (DFT) and in-situ tests uncover that FeTeO heterojunction substrates can further boost the HER activity by modulating the electronic structure and H adsorption energy. Consequently, the as-prepared Ru/FeTeO possesses outstanding HER activity with low overpotentials of 244 and 311 mV to drive 1.0 and 3.0 A cm−2 current densities in 1.0 M KOH seawater solution, respectively, and displays a long-term stability more than 150 h. This work supplies an effective way to stimulate the intrinsic activity of precious metals. [Display omitted] • The FeTeO heterojunction substrates can enhance the bonding interactions. • The Ru/FeTeO show overpotentials of 311 mV to drive 3 A cm−2 current density. • DFT show that FeTeO heterojunction substrates modulate H adsorption energy of Ru. [ABSTRACT FROM AUTHOR]

The development of efficient and stable oxygen reduction reaction (ORR) electrocatalysts in seawater electrolyte is the key to realizing marine resource utilization and expanding metal-air battery applications. Herein, defect-rich Fe-doped Co nanoparticles encapsulated by N-doped hierarchical carbon (D- Fe Co@NHC) are rationally designed and synthesized. It is worth mentioning that the Fe doping helps to promote the generation of metal defect and adjust the electronic structure of D- Fe Co@NHC. Density functional theory (DFT) demonstrate that the metal defect and carbon defect jointly optimize the d -band center of D- Fe Co@NHC. As a result, in alkaline seawater electrolyte, D- Fe Co@NHC display a half-wave potential of 0.874 V, and the assembled liquid Zn-air battery exhibit a high peak power density (173 mW cm−2) and ultra-long cycling stability (over 800 h). This work highlights the defect engineering in the construction of seawater-based oxygen reduction electrocatalysts, which provide a significant and promising approach for seawater-based metal-air cathode materials. In this work, defect-rich Fe-doped Co nanoparticles encapsulated by N-doped hierarchical carbon (D- Fe Co@NHC) are rationally designed and synthesized. Notably, the influence mechanism of Cl- in seawater on ORR activity of D- Fe Co@NHC catalyst is determined. Furthermore, the as-prepared D- Fe Co@NHC displays excellent ORR activity with half-wave potential of 0.874 V in 1.0 M KOH + seawater. [Display omitted] • Defect-rich Fe-doped Co encapsulated by N-doped hierarchical carbon was synthesized. • The as-prepared D- Fe Co@NHC displays excellent ORR activity in 1.0 M KOH + seawater. • The seawater-based Zn-air battery was assembled by D- Fe Co@NHC as an air cathode. • Metal defect and carbon defect jointly optimize the d-band center of D- Fe Co@NHC. [ABSTRACT FROM AUTHOR]

Despite the relatively rich literature on the omnipresence of microplastics in marine environments, the current status and ecological impacts of microplastics on global Marine Protected Areas (MPAs) are still unknown. Their ubiquitous occurrence, increasing volume, and ecotoxicological effects have made microplastic an emerging marine pollutant. Given the critical conservation roles of MPAs that aim to protect vulnerable marine species, biodiversity, and resources, it is essential to have a comprehensive overview of the occurrence, abundance, distribution, and characteristics of microplastics in MPAs including their buffer zones. Here, extensive data were collected and screened based on 1565 peer-reviewed literature from 2017 to 2020, and a GIS-based approach was applied to improve the outcomes by considering boundary limits. Microplastics in seawater samples were verified within the boundaries of 52 MPAs; after including the buffer zones, 1/3 more (68 MPAs) were identified as contaminated by microplastics. A large range of microplastic levels in MPAs was summarized based on water volume (0–809,000 items/m3) or surface water area (21.3–1,650,000,000 items/km2), which was likely due to discrepancy in sampling and analytical methods. Fragment was the most frequently observed shape and fiber was the most abundant shape. PE and PP were the most common and also most abundant polymer types. Overall, 2/3 of available data reported that seawater microplastic levels in MPAs were higher than 12,429 items/km2, indicating that global MPAs alone cannot protect against microplastic pollution. The current limitations and future directions were also discussed toward the post-2020 Global Biodiversity Framework goals. [Display omitted] • Microplastic (MP) contamination on MPAs was evaluated on a global scale. • GIS-based vector analysis was used to overcome the boundary limits of MPAs. • 1/3 more MPAs were identified as contaminated by MPs after considering buffer zone. • Fiber was the most abundant shape and PE and PP are the dominant polymer types. • 2/3 of data showed seawater MP levels higher than 12,429 items/km2 in MPAs. [ABSTRACT FROM AUTHOR]

Due to the shortage of global freshwater resources and sufficient seawater resources, electrolysis of seawater has become a research hotspot. However, the presence of chloride ions in seawater greatly hinders the development of seawater electrolysis, therefore, constructing catalyst with high catalytic activity and stability against chloride corrosion is essential for seawater electrolysis. In this work, we synthesize F doped FeP and CoP nanosheets with P vacancies (F-FeCoP v @IF) by rapidly molten salt and gas-phase phosphorization strategy, which displays bifunctional activity for HER and OER in alkaline seawater. And the assembled F-FeCoP v @IF needs 1.94 V and 1.62 V to drive 1000 mA cm−2 for overall seawater splitting in alkaline seawater and simulated industrial seawater. And the F-FeCoP v @IF has outstanding long-term durability for over 100 h and nearly 100% FE. DFT calculations reveal that F-doping and P vacancies can synergistically modulate the electronic structure of FeCoP, which enable F-FeCoP v @IF serve as excellent bifunctional electrocatalyst. [Display omitted] • We synthesize F/Fe-CoP v @IF nanosheet by molten salt and gas-phase phosphorization. • F/Fe-CoP v @IF exhibits bifunctional electrocatalytic activity in alkaline seawater. • F/Fe-CoP v @IF needs 1.94 V to drive 1000 mA cm−2 for overall seawater splitting. • F-doping and P vacancy synergistically tune the electronic structure of Fe-CoP. [ABSTRACT FROM AUTHOR]

Using Cu-CoFe/Co/NC as trifunctional electrocatalysts in alkaline seawater, an overall hydrazine splitting (OHzS) unit is self-powered by a direct hydrazine fuel cell (DHzFC), demonstrating the great potential of Cu-CoFe/Co/NC as trifunctional electrocatalysts toward energy storage and conversion devices. [Display omitted] • Cu-doped CoFe/Co encapsulated by N -doped carbon (Cu-CoFe/Co/NC) is synthesized. • The electronic structure and d-band center of catalyst are regulated. • The catalyst show good ORR, HzOR and HER performance in alkaline seawater. • The catalyst is used into direct hydrazine fuel cell and overall hydrazine splitting. The development of high-performance and robust electrocatalyst suitable for oxygen reduction reaction (ORR), hydrazine oxidation reaction (HzOR), and hydrogen evolution reaction (HER) in seawater still faces huge challenges. In this study, Cu-doped CoFe/Co encapsulated by N -doped carbon (Cu-CoFe/Co/NC) is synthesized via chemical precipitation followed by carbonization method, in which the electronic structure and d-band center of Cu-CoFe/Co/NC are regulated by metal doping and hetero-engineering. The as-synthesized Cu-CoFe/Co/NC exhibit excellent electrocatalytic activity for ORR (E 1/2 = 0.87 V), HzOR (η 10 = 281 mV), and HER (η -10 = 217 mV) in alkaline seawater. Inspiringly, the self-assembled direct hydrazine fuel cell (DHzFC) are used to power overall hydrazine splitting (OHzS) for proof of concept, demonstrating the great potential of Cu-CoFe/Co/NC as trifunctional electrocatalyst toward energy storage and conversion devices. [ABSTRACT FROM AUTHOR]