Highly Durable and Efficient Seawater Electrolysis Enabled by Defective Graphene-Confined Nanoreactor

Gong, Zhichao; Liu, Jingjing; Yan, Minmin; Gong, Haisheng; Ye, Gonglan; Fei, Huilong

doi:10.1021/acsnano.3c05749

“…However, achieving direct seawater electrocatalysis is still a challenge in terms of techno-commercial aspects due to the complex composition of seawater and the sluggish anodic oxygen evolution reaction (OER) . Indeed, the concentrations of chloride ion (Cl – ) and its derivatives like hypochlorite (ClO – ) are high in the seawater, while the subsequent chlorine oxidation reaction and chloride-hydroxide formation reaction upon seawater electrocatalysis could seriously degrade the OER catalyst rapidly, followed by the impediment of seawater-splitting efficiency for practical seawater electrocatalysis . Furthermore, the photogenerated holes are hindered from reaching the interface for efficient transfer into the photoanode-electrolyte solution for water oxidation, leading to increased charge recombination rates that suppress the OER activity. , Several electrocatalysts such as porous S-doped Ni/Fe (oxy) hydroxides, CeO x -coated NiFeO x , non-noble metal phosphides, nitrides, and selenide-based electrocatalysts have been recently demonstrated to be efficient earth-abundant OER catalysts for seawater electrocatalysis − However, anodic corrosion, selective Cl – repulsion, long-term stability, and attaining a high performance of the electrocatalyst in direct seawater electrocatalysis remain to be impeded and thus, it is necessitated to develop innovative strategies to design an efficient OER catalyst to elevate the exclusive trade-off factors between stability and performance issues …”

Section: Introductionmentioning

confidence: 99%

Ultrastable, High Photoelectrocatalytic Performance of Altervalent Cation-Doped BiVO₄ Photoanode and Effect of Interfacial Contact with Nanoporous Carbon for Seawater Splitting Using a 3D-Printed Flow Device

Dabodiya,

George,

Mathew

et al. 2024

ACS Appl. Energy Mater.

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Solar-driven direct seawater electrocatalysis is a promising technology for sustainable large-scale green-H 2 fuel generation. In this work, we systematically investigate the influence of altervalent cation doping into the Bi 3+ and V 5+ sites of scheelite BiVO 4 via a sustainable microwave-assisted hydrothermal (MW-HT) technique within a few minutes (12 min) at as low a temperature of 190 °C. We observed that lower-valent cation (Cs + , Ba 2+ , Co 2+ , and In 3+ ) doping favors monoclinic-phase formation; however, higher-valent cations (Hf 4+ , Nb 5+ , and Mo 6+ ) facilitated the thermodynamically unfavorable tetragonal-zircon type BiVO 4 . Interestingly, mixed phases of monoclinic-tetragonal BiVO 4 have been obtained upon codoping of Co and Mo, exhibiting enhanced photocurrent density (J p = 5.8 mA cm −2 ) among other doped BiVO 4 samples. To increase the overall charge-transfer kinetics, we construct a nanoporous carbon with a Co and Mo codoped BiVO 4 hybrid photoanode showing a remarkable (∼5-fold) enhancement in photoelectrochemical (PEC) freshwater splitting with the highest recorded photocurrent density of J p = 6.9 mA cm −2 at 1.23 V vs RHE, AM1.5 G in 0.5 M Na 2 SO 4 electrolyte solution, in comparison to pristine BiVO 4 (1.45 mA cm −2 ) under simulated visible light. The superior performance is due to oxygen vacancy (OV)-related defect levels functioning as electron-trap sites promoting fast charge separation and surface adsorption for generating excess holes at the nanohybrid photoanode. In order to investigate how the nanohybrid photoanode affects the charge-carrier recombination rate and oxygen evolution reaction (OER) in seawater, we designed a compartmentalized three-dimensional (3D)-printed membrane-less, continuous-flow PEC device to produce massive H 2 fuel. Significantly, we observed an enhanced J p of 3.8 mA cm −2 accompanied by an outstanding long-term photostability of 4 h, achieved due to the rapid transfer of photostimulated holes from the nanohybrid photoanode to the electrolyte, promoted by the internal electric field over the constructed Mott−Schottky heterostructure. Thus, our work explicates the innovative design of a nanohybrid photoanode playing a crucial role in the efficient electronic interactions in the space-charge layer between the photoanode and seawater-electrolyte interface for effective seawater splitting.

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“…NiFe‐based materials (NFMs), as an undoubtedly cheap OER catalyst candidate, reveal promising activities in alkaline media, hence they are the vital focus of research [8,16,25–30] . Redox behaviors of NFMs under polarized anodic oxidation conditions usually produce high metal valence oxyhydroxides (e.g., γ‐NiOOH), [31–33] contributing to high catalytic activities.…”

Section: Introductionmentioning

confidence: 99%

“…NiFe-based materials (NFMs), as an undoubtedly cheap OER catalyst candidate, reveal promising activities in alkaline media, hence they are the vital focus of research. [8,16,[25][26][27][28][29][30] Redox behaviors of NFMs under polarized anodic oxidation conditions usually produce high metal valence oxyhydroxides (e.g., γ-NiOOH), [31][32][33] contributing to high catalytic activities. However, such metal sites can hardly survive under corrosive Cl À -rich environments in that highly aggressive chlorine chemistry corrodes them easily, especially at the strong anodic polarization conditions.…”

Section: Introductionmentioning

confidence: 99%

Carbon Oxyanion Self‐Transformation on NiFe Oxalates Enables Long‐Term Ampere‐Level Current Density Seawater Oxidation

Li,

Yao,

Sun

et al. 2023

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Seawater electrolysis is an attractive way of making H2 in coastal areas, and NiFe‐based materials are among the top options for alkaline seawater oxidation (ASO). However, ample Cl− in seawater can severely corrode catalytic sites and lead to limited lifespans. Herein, we report that in situ carbon oxyanion self‐transformation (COST) from oxalate to carbonate on a monolithic NiFe oxalate micropillar electrode allows safeguard of high‐valence metal reaction sites in ASO. In situ/ex situ studies show that spontaneous, timely, and appropriate COST safeguards active sites against Cl− attack during ASO even at an ampere‐level current density (j). Our NiFe catalyst shows efficient and stable ASO performance, which requires an overpotential as low as 349 mV to attain a j of 1 A cm−2. Moreover, the NiFe catalyst with protective surface CO32− exhibits a slight activity degradation after 600 h of electrolysis under 1 A cm−2 in alkaline seawater. This work reports effective catalyst surface design concepts at the level of oxyanion self‐transformation, acting as a momentous step toward defending active sites in seawater‐to‐H2 conversion systems.

show abstract

“…NiFe-based materials (NFMs), as an undoubtedly cheap OER catalyst candidate, reveal promising activities in alkaline media, hence they are the vital focus of research. [8,16,[25][26][27][28][29][30] Redox behaviors of NFMs under polarized anodic oxidation conditions usually produce high metal valence oxyhydroxides (e.g., γ-NiOOH), [31][32][33] contributing to high catalytic activities. However, such metal sites can hardly survive under corrosive Cl À -rich environments in that highly aggressive chlorine chemistry corrodes them easily, especially at the strong anodic polarization conditions.…”

Section: Introductionmentioning

confidence: 99%

“…NiFe‐based materials (NFMs), as an undoubtedly cheap OER catalyst candidate, reveal promising activities in alkaline media, hence they are the vital focus of research [8,16,25–30] . Redox behaviors of NFMs under polarized anodic oxidation conditions usually produce high metal valence oxyhydroxides (e.g., γ‐NiOOH), [31–33] contributing to high catalytic activities.…”

Section: Introductionmentioning

confidence: 99%

Carbon Oxyanion Self‐Transformation on NiFe Oxalates Enables Long‐Term Ampere‐Level Current Density Seawater Oxidation

Li,

Yao,

Sun

et al. 2023

View full text Add to dashboard Cite

Seawater electrolysis is an attractive way of making H2 in coastal areas, and NiFe‐based materials are among the top options for alkaline seawater oxidation (ASO). However, ample Cl− in seawater can severely corrode catalytic sites and lead to limited lifespans. Herein, we report that in situ carbon oxyanion self‐transformation (COST) from oxalate to carbonate on a monolithic NiFe oxalate micropillar electrode allows safeguard of high‐valence metal reaction sites in ASO. In situ/ex situ studies show that spontaneous, timely, and appropriate COST safeguards active sites against Cl− attack during ASO even at an ampere‐level current density (j). Our NiFe catalyst shows efficient and stable ASO performance, which requires an overpotential as low as 349 mV to attain a j of 1 A cm−2. Moreover, the NiFe catalyst with protective surface CO32− exhibits a slight activity degradation after 600 h of electrolysis under 1 A cm−2 in alkaline seawater. This work reports effective catalyst surface design concepts at the level of oxyanion self‐transformation, acting as a momentous step toward defending active sites in seawater‐to‐H2 conversion systems.

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Highly Durable and Efficient Seawater Electrolysis Enabled by Defective Graphene-Confined Nanoreactor

Cited by 26 publications

References 46 publications

Ultrastable, High Photoelectrocatalytic Performance of Altervalent Cation-Doped BiVO₄ Photoanode and Effect of Interfacial Contact with Nanoporous Carbon for Seawater Splitting Using a 3D-Printed Flow Device

Ultrastable, High Photoelectrocatalytic Performance of Altervalent Cation-Doped BiVO₄ Photoanode and Effect of Interfacial Contact with Nanoporous Carbon for Seawater Splitting Using a 3D-Printed Flow Device

Carbon Oxyanion Self‐Transformation on NiFe Oxalates Enables Long‐Term Ampere‐Level Current Density Seawater Oxidation

Carbon Oxyanion Self‐Transformation on NiFe Oxalates Enables Long‐Term Ampere‐Level Current Density Seawater Oxidation

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Highly Durable and Efficient Seawater Electrolysis Enabled by Defective Graphene-Confined Nanoreactor

Cited by 26 publications

References 46 publications

Ultrastable, High Photoelectrocatalytic Performance of Altervalent Cation-Doped BiVO4 Photoanode and Effect of Interfacial Contact with Nanoporous Carbon for Seawater Splitting Using a 3D-Printed Flow Device

Ultrastable, High Photoelectrocatalytic Performance of Altervalent Cation-Doped BiVO4 Photoanode and Effect of Interfacial Contact with Nanoporous Carbon for Seawater Splitting Using a 3D-Printed Flow Device

Carbon Oxyanion Self‐Transformation on NiFe Oxalates Enables Long‐Term Ampere‐Level Current Density Seawater Oxidation

Carbon Oxyanion Self‐Transformation on NiFe Oxalates Enables Long‐Term Ampere‐Level Current Density Seawater Oxidation

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Ultrastable, High Photoelectrocatalytic Performance of Altervalent Cation-Doped BiVO₄ Photoanode and Effect of Interfacial Contact with Nanoporous Carbon for Seawater Splitting Using a 3D-Printed Flow Device

Ultrastable, High Photoelectrocatalytic Performance of Altervalent Cation-Doped BiVO₄ Photoanode and Effect of Interfacial Contact with Nanoporous Carbon for Seawater Splitting Using a 3D-Printed Flow Device