“…Construction of core‐shell configuration to form the heterojunction and favorable band bending for charge carriers generation and transportation has been demonstrated as an effective strategy to overcome these shortcomings, where a shell coating can endow a photoelectrode with improved activity and stability. [ 28 ] At present, many kinds of core‐shell photoelectrodes with various composition and properties have been developed for PEC water splitting. In this section, we highlight the compositions of core‐shell photoelectrode.…”
Section: Core‐shell Tandem Nanostructured Photoelectrode For Pec Wate...mentioning
A platform for efficient photoelectrochemical (PEC) water splitting must fulfil different requirements: the absorption of the solar spectrum should be maximized in use for charge carrier generation. To avoid recombination, fast separation of charge carriers is required and the energetic positions of the band structure(s) must be optimized with respect to the water splitting reactions. In these respects, constructing tandem nanostructures with rationally designed nanostructured units offers a potential opportunity to break the performance bottleneck imposed by the unitary nanostructure. So far, quite a few tandem nanostructures have been designed, fabricated, and employed to improve the efficiency of PEC water splitting, and significant achievements have been realized. This review focuses on the current advances in tandem nanostructures for PEC water splitting. Firstly, the state of the art for tandem nanostructures applied in PEC water splitting is summarized. Secondly, the advances in this field and advantages arising of employing tandem nanostructures for PEC water splitting are outlined. Subsequently, different types of tandem nanostructures are reviewed, including core‐shell tandem nanostructured photoelectrode, the two‐photoelectrode tandem cell, and the tandem nanostructures of plasmon related devices for PEC water splitting. Based on this, the future perspective of this field is proposed.
“…Construction of core‐shell configuration to form the heterojunction and favorable band bending for charge carriers generation and transportation has been demonstrated as an effective strategy to overcome these shortcomings, where a shell coating can endow a photoelectrode with improved activity and stability. [ 28 ] At present, many kinds of core‐shell photoelectrodes with various composition and properties have been developed for PEC water splitting. In this section, we highlight the compositions of core‐shell photoelectrode.…”
Section: Core‐shell Tandem Nanostructured Photoelectrode For Pec Wate...mentioning
A platform for efficient photoelectrochemical (PEC) water splitting must fulfil different requirements: the absorption of the solar spectrum should be maximized in use for charge carrier generation. To avoid recombination, fast separation of charge carriers is required and the energetic positions of the band structure(s) must be optimized with respect to the water splitting reactions. In these respects, constructing tandem nanostructures with rationally designed nanostructured units offers a potential opportunity to break the performance bottleneck imposed by the unitary nanostructure. So far, quite a few tandem nanostructures have been designed, fabricated, and employed to improve the efficiency of PEC water splitting, and significant achievements have been realized. This review focuses on the current advances in tandem nanostructures for PEC water splitting. Firstly, the state of the art for tandem nanostructures applied in PEC water splitting is summarized. Secondly, the advances in this field and advantages arising of employing tandem nanostructures for PEC water splitting are outlined. Subsequently, different types of tandem nanostructures are reviewed, including core‐shell tandem nanostructured photoelectrode, the two‐photoelectrode tandem cell, and the tandem nanostructures of plasmon related devices for PEC water splitting. Based on this, the future perspective of this field is proposed.
“…ALDfabricated thin films are commonly used as protective coatings in numerous electrochemical applications. [8] The unique nanoshell fabricated using AER and ALD presented the advantages of the active material and passivation layer. The durability of NCS/NiS-10 in oxidizing and reducing environments after 10 days of continuous operation was outstanding, and the NCS/NiS-10 electrocatalyst outperformed many recently reported metal sulfide electrocatalysts (Table S1, Supporting Information).…”
Section: Overall Electrocatalytic Water-splitting Performance Of the ...mentioning
confidence: 99%
“…[7] ALD allows the deposition of one atom layer at a time, thereby facilitating thickness control at the atomic level. [8] The surfaces of ALD-fabricated layers are strain-free and smooth; therefore, their N A values are small. In this study, we used ALD to deposit NiO nanoshells on NiCo 2 O 4 (NC) cores.…”
nontoxic, abundant, and durable catalysts with high activity toward the oxygen and hydrogen evolution reactions (OER and HER, respectively) are preferred. [3] Electrode material and architecture play critical roles in electrocatalytic water splitting. [4] Electrochemical reactions occur at the electrode-electrolyte interface; therefore, electrochemical processes are interfacedependent. Typically, only a fraction of the exposed sites, namely the surface active sites, participates in the electrochemical charge transfer process (Scheme 1a). The electrochemically active surface area (ECSA) generated by the electrical double layer formed at the electrode-electrolyte interface features numerous inactive surface sites that do not participate in electrochemical charge transfer (electronation-deelectronation). Building 3D architectures with large ECSAs is a common method for increasing active surface sites and accelerating electrochemical water splitting (Scheme 1b). In particular, coreshell architectures are highly desirable for good electrode performance because they combine the distinct properties of the core and shell materials used to build multifunctional electrodes. [5] For example, core-shell electrodes with NiCo 2 S 4 (NCS) cores and various shell structures have been evaluated for electrocatalytic water splitting. [6] However, coreshell architectures lengthen the electron transport pathways and increase electrode mass and interfacial resistance, hindering the efficient electrode utilization. The increase in total mass results in lower mass activity, although the estimated electrochemical performance of the core-shell structure is superior to that of the core structure as a function of the geometric area of the electrodes. Hence, developing innovative electrode nano-architectures to increase the N A with higher mass activity is an important task for developing commercial electrochemical energy conversion and storage devices. Nano-roughening the outer surfaces of nanostructures is an advanced method for increasing N A . It has similar ECSAs compared to conventional core-shell structures, but a greater proportion of active sites and massive mass activity. The ECSAs of the structures in Scheme 1b,d are the same; however, the ratio of active to inactive sites of the structure in Scheme 1d is higher than that of the structure in Scheme 1b. This can be achieved using several approaches, such as top-down physical etching, controlled Electrocatalytic water splitting, which is an interface-dominated process, can be significantly accelerated by increasing the number of front-line surface active sites (N A ) of the electrocatalyst. In this study, a unique method is used for increasing the N A by converting the smooth ultrathin atomic-layer-deposited nanoshells of the electrocatalysts into nano-roughened active shell layers using a controlled anion-exchange reaction (AER). The coarse thin nanoshells present abundant surface active sites, which are generated owing to the inherent unit-cell volume mismatch induced during th...
“…The surface and interface engineering strategy in particular has the potential to improve the electrochemical features of electrode materials. − Interface engineering can be carried out by coating a thin metal oxide layer over a core/shell architecture through atomic layer deposition (ALD). ALD is a unique process to achieve conformal coating of ultrathin layers and allow the control of atomic-scale thickness. , A recent study demonstrated that a Co 9 S 8 conformal layer over nickel foam led to excellent performance of a supercapacitor . Among metal oxides, nickel oxide (NiO) is typically used as the outer shell layer because it is a low-cost, readily available, and environmentally friendly material that exhibits excellent conductivity, high theoretical capacity, and mechanical stability. , Additionally, NiO facilitates fast redox reactions with a long cycling duration, which is considered to be important for achieving superior supercapacitive performance …”
Section: Introductionmentioning
confidence: 99%
“…ALD is a unique process to achieve conformal coating of ultrathin layers and allow the control of atomic-scale thickness. 28,29 A recent study demonstrated that a Co 9 S 8 conformal layer over nickel foam led to excellent performance of a supercapacitor. 30 Among metal oxides, nickel oxide (NiO) is typically used as the outer shell layer because it is a low-cost, readily available, and environmentally friendly material that exhibits excellent conductivity, high theoretical capacity, and mechanical stability.…”
Owing to their low cost, transition
metal layered double hydroxides
(LDHs) have the potential to become the electrode material of choice
for supercapacitors if they can provide good cyclic stability and
high specific capacity. Herein, we introduce an approach for forming
a high-quality, uniform thin film of nickel oxide (NiO) that can act
as an auxiliary nickel oxyhydroxide (NiOOH) layer during redox cycling
in an alkaline electrolyte. This approach leads to a core/double-shell
NiCo-LDH/NiOOH/ALD-NiO electrode that exhibits an unprecedented specific
capacity of 1420.2 C g–1 (even at 4 A g–1), retaining 93% of the capacity after 20,000 cycles. Even when combined
with a simple anode of activated carbon, an asymmetric supercapacitor
with this cathode provides an energy density of 72.6 W h kg–1 with exceptional durability (9.1% loss over 10,000 cycles). This
extraordinary electrode when combined with an articulated anode in
a supercapacitor is expected to meet or exceed the current energy
density limit of lithium-ion batteries.
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