Ni single atoms on carbon nitride for visible-light-promoted full heterogeneous dual catalysis

Kwak, Minjoon; Bok, Jinsol; Lee, Byoung‐Hoon; Kim, Jongchan; Seo, Yutaek; Kim, Sumin; Choi, Hyunwoo; Ko, Wonjae; Antink, Wytse Hooch; Lee, Chan Woo; Yim, Guk Hee; Seung, Hyojin; Park, Chansul; Lee, Kug‐Seung; Kim, Dae‐Hyeong; Hyeon, Taeghwan; Yoo, Dongwon

doi:10.1039/d2sc02174a

Cited by 30 publications

(35 citation statements)

References 39 publications

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“…68,69 The peak approaching 850 eV in Figure 8d−f confirms the presence of Ni 0 in samples that underwent the HER. 61,70,71 As estimated by the peak area, it was noticed that NiO(65)/CN x after the HER has the highest amount of Ni 0 species (7%), followed by Ni/CN x after the HER (5%), and finally Ni/TiO 2 after the HER (2%). The trend in the amount of Ni 0 species in the samples conforms with the trend in the HER activity, strongly suggesting that the activity difference among NiO/CN x samples is caused by the different Ni 0 content.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…A partially surface oxidized Ru/RuO 2 NPs outcompeted commercial Pt/C in alkaline solution, while in an acidic environment, a continuous decrease of Ru IV for generating more reactive metallic Ru 0 for the electrocatalytic HER is noticed. Later in Kwak et al’s work, CN x was functionalized with single Ni atoms for photocatalytic hydrogen evolution, and the coexistence of Ni 0 and Ni II species was confirmed after sample preparation . The Ni peak positions and the ratio of Ni 0 /Ni II remain almost identical after the HER, suggesting the well-maintained Ni oxidation states.…”

Section: Resultsmentioning

confidence: 99%

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ALD-Deposited NiO Approaches the Performance of Platinum as a Hydrogen Evolution Cocatalyst on Carbon Nitride

Liu

Godin

2022

ACS Catal.

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The photocatalytic hydrogen evolution reaction is one of the most promising approaches to utilize solar energy and produce hydrogen as an alternative energy source to traditional fossil fuels. In this work, we focused on further exploring the cocatalyst potential of the transition metal nickel and prepared nickel oxide/ carbon nitride (NiO/CN x ) heterojunctions through thermal polymerization as well as plasma-enhanced atomic layer deposition (PEALD). The optimal NiO loading thickness on the surface of the CN x was found to be 6.5 nm, prepared from 65 cycles of ALD. This NiO(65)/CN x had a photocatalytic hydrogen evolution rate of 3.9 μmol h −1 in a 2 mg mL −1 aqueous photocatalyst solution (195 μmol h −1 g −1 ), corresponding to an AQY of 3.1% and exhibiting 54% of the activity of 3 wt % Pt/CN x under 405 nm light illumination with a sacrificial reagent. A 3 wt % Ni/CN x prepared through a photodeposition process from a dispersion of CN x and simple NiCl 2 had a photocatalytic hydrogen evolution rate of 2.8 μmol h −1 (140 μmol h g −1 ) and an AQY of 2.2% with 2 mg mL −1 photocatalyst in the reactant solution, corresponding to 39% of the activity of 3 wt % Pt/CN x . An induction period at the beginning of the hydrogen evolution process was found in all Ni-based photocatalysts, which we related to a Ni in situ photoreduction from Ni II to Ni 0 and the reverse reaction. In addition, the reproducibility of the induction period even in an oxygen-free environment suggests that electrons flow back from reduced Ni species to CN x under dark conditions. Furthermore, a large population of trap states was detected in the bulk CN x materials via photoinduced absorption spectroscopy, and the trapping severely hinders cocatalysts (even the benchmark Pt cocatalyst) from extracting charges from CN x for subsequent interfacial redox reactions. We conclude that not only does the surface/interface engineering of the photocatalyst/ catalyst heterojunctions need to be considered but also trap states in CN x that severely limit the transfer of photogenerated charges to cocatalysts.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

ALD-Deposited NiO Approaches the Performance of Platinum as a Hydrogen Evolution Cocatalyst on Carbon Nitride

Liu

Godin

2022

ACS Catal.

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“…In 2022, Yoo and collaborators employed a wet impregnation synthetic protocol, which was followed by low‐temperature calcination in a reductive atmosphere, to obtain a new Ni‐single atom CN, labelled Ni‐SACN‐2 (Figure 5a) [26] . Ni‐SACN‐2 was used to catalyze the cross‐coupling reaction between aryl bromides 1 a and cyclic secondary amines 5 affording the corresponding aniline derivatives ( 4 , Figure 5b).…”

Section: Application Of Sacn Catalysts For Light‐driven Processesmentioning

confidence: 99%

“… a) Synthetic scheme for Ni‐SACN‐2 preparation. b) Application of Ni‐SACN‐2 for the cross‐coupling reaction of aryl bromides and secondary amines [26] …”

Section: Application Of Sacn Catalysts For Light‐driven Processesmentioning

confidence: 99%

“…It is worth noting that the metal‐support interactions, between the anchored single atoms and the CNs, lead to the formation of new electronic states, which modify the photocatalytic properties of the material [22] . Although the use of carbon nitrides in organic photocatalysis is fairly recent, examples describing the applications of CN‐based SACs for the effective production of relevant organic molecules have been reported in the last few years [20,23–26] . Mechanistically, visible‐light irradiation may induce electron transfer processes within the photocatalytic system, thus altering the oxidation state of surface metal atoms.…”

Section: Introductionmentioning

confidence: 99%

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Use of Carbon Nitrides as Photoactive Supports in Single‐Atom Heterogeneous Catalysis for Synthetic Purposes

et al. 2022

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In recent years, the field of dual photocatalysis has become an increasingly popular tool for the functionalization of organic substrates under mild operative conditions. Single-atom heterogeneous catalysts (SACs), where the metal atoms are stabilized by means of properly structured photoactive supports, are currently one of the frontiers of this research field. To this end, Carbon Nitrides (CNs) have emerged as ideal two-dimensional semiconducting supports, capable of stabilizing single metal sites (for instance: nickel, iron, among other) through nitrogenrich structures. This Concept highlights the recent advances in the synthesis of carbon nitride-based SACs and their applications in light-driven dual-catalytic processes, also providing forward-looking opportunities within this research area.

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Single‐Atom Catalysis in Organic Synthesis

et al. 2023

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Single‐atom catalysts hold the potential to significantly impact the chemical sector, pushing the boundaries of catalysis in new, uncharted directions. These materials, featuring isolated metal species ligated on solid supports, can exist in many coordination environments, all of which have shown important functions in specific transformations. Their emergence has also provided exciting opportunities for mimicking metalloenzymes and bridging the gap between homogeneous and heterogeneous catalysis. This Review outlines the impressive progress made in recent years regarding the use of single‐atom catalysts in organic synthesis. We also illustrate potential knowledge gaps in the search for more sustainable, earth‐abundant single‐atom catalysts for synthetic applications.

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Ni single atoms on carbon nitride for visible-light-promoted full heterogeneous dual catalysis

Abstract: Visible-light-driven organic transformations are of great interest in synthesizing valuable fine chemicals under mild conditions. The merger of heterogeneous photocatalysts and transition metal catalysts has recently drawn much attention due...

Cited by 30 publications

References 39 publications

ALD-Deposited NiO Approaches the Performance of Platinum as a Hydrogen Evolution Cocatalyst on Carbon Nitride

ALD-Deposited NiO Approaches the Performance of Platinum as a Hydrogen Evolution Cocatalyst on Carbon Nitride

Use of Carbon Nitrides as Photoactive Supports in Single‐Atom Heterogeneous Catalysis for Synthetic Purposes

Single‐Atom Catalysis in Organic Synthesis

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