scholarly journals Engineering active sites on reduced graphene oxide by hydrogen plasma irradiation: mimicking bifunctional metal/supported catalysts in hydrogenation reactions

2018 ◽  
Vol 20 (11) ◽  
pp. 2611-2623 ◽  
Author(s):  
Ana Primo ◽  
Antonio Franconetti ◽  
Monica Magureanu ◽  
Nicolae Bogdan Mandache ◽  
Cristina Bucur ◽  
...  

H2 plasma generates carbon vacancies on reduced graphene oxide increasing its activity as a hydrogenation catalyst.

Author(s):  
Hang Lei ◽  
Shangjing Yang ◽  
Runquan Lei ◽  
Qing Zhong ◽  
Qixiang Wan ◽  
...  

Insufficient catalytic activity and self-restacking of 2D MXenes during catalytic processes would lead to limited number of active sites, sluggish ionic kinetics and poor durability, extremely restricting its application in...


NANO ◽  
2020 ◽  
Vol 15 (02) ◽  
pp. 2050021
Author(s):  
Qi Tang ◽  
Menghan Ye ◽  
Li Ma ◽  
Tao Zhou ◽  
Mengyu Gan ◽  
...  

In this work, the Ni–Mn layered double hydroxide (Ni–Mn LDH) nanopetals are fabricated on three-dimensional reduced graphene oxide/Ni foam (RGO/NF) by one-step hydrothermal method, in which the suspension of graphene oxide (GO) is directly reduced by nickel foam (NF) to obtain NF/RGO. The composite, which consists of interconnected Ni–Mn LDH nanopetals, forms a macroporous structure. Such an open space can promote electrolyte dispersion and ion diffusion of active substances, thus enhancing capacitance performance. Remarkable, during crystal growth, RGO can not only provide active sites for Ni–Mn LDH nanopetals, but also effectively connect Ni–Mn LDH nanopetals to NF, further promoting the electrochemical behavior of composite material. Moreover, RGO possess reasonable chemical stability which can improve the mechanical properties of the composite to obtain good stability. The experimental results show that the NF/RGO electrode material with Ni–Mn LDH nanopetals has excellent specific capacitance of 2250[Formula: see text]F[Formula: see text]g[Formula: see text] at 1[Formula: see text]A[Formula: see text]g[Formula: see text], good rate performance (the capacitance retention rate is still 64.0% at 10[Formula: see text]A[Formula: see text]g[Formula: see text] and excellent cycle life (45.1% at 10[Formula: see text]A[Formula: see text]g[Formula: see text] after 5000 cycles). NR/NM–LDH is used as the positive electrode and activated carbon is used as the negative electrode to assemble the asymmetric supercapacitor, the proper power density and energy density indicates that the NR/NM–LDH composite has great potential as an electrode material for supercapacitors.


Catalysts ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 948
Author(s):  
Chen Zhao ◽  
Zhi Yu ◽  
Jun Xing ◽  
Yuting Zou ◽  
Huiwen Liu ◽  
...  

The development of efficient electrocatalyst to produce molecular hydrogen from water is receiving considerable attention, in an effort to decrease our reliance on fossil fuels. The prevention of the aggregation of active sites during material synthesis, in order to increase charge transport properties of electrocatalysts, is needed. We have designed, synthesized, and studied a Ag2S/reduced graphene oxide (rGO) electrochemical catalyst (for hydrogen evolution) from water. The Ag2S nanocrystals were synthesized by the solvothermal method in which the rGO was added. The addition of the rGO resulted in the formation of smaller Ag2S nanocrystals, which consequently increased the electrical conductivity of the composite catalyst. The composite catalyst showed a higher electrochemical catalytic activity than the one with an absence of rGO. At a current density of 10 mA/cm2, a low overpotential of 120 mV was obtained. A Tafel slope of 49.1 mV/dec suggests a Volmer–Herovsky mechanism for the composite catalyst. These results may provide a novel strategy for developing hydrogen evolution reaction (HER) electrocatalysts, via the combining of a nano-semiconductor catalyst with a 2D material.


2019 ◽  
Vol 7 (19) ◽  
pp. 15948-15956 ◽  
Author(s):  
Juan C. Espinosa ◽  
Mercedes Álvaro ◽  
Amarajothi Dhakshinamoorthy ◽  
Sergio Navalón ◽  
Hermenegildo García

Nanomaterials ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 1084 ◽  
Author(s):  
Quan Sun ◽  
Ying Huang ◽  
Shi Wu ◽  
Zhonghui Gao ◽  
Hang Liu ◽  
...  

Sn/Nitrogen-doped reduced graphene oxide (Sn@N-G) composites have been successfully synthesized via a facile method for lithium-ion batteries. Compared with the Sn or Sn/graphene anodes, the Sn@N-G anode exhibits a superb rate capability of 535 mAh g−1 at 2C and cycling stability up to 300 cycles at 0.5C. The improved lithium-storage performance of Sn@N-G anode could be ascribed to the effective graphene wrapping, which accommodates the large volume change of Sn during the charge–discharge process, while the nitrogen doping increases the electronic conductivity of graphene, as well as provides a large number of active sites as reservoirs for Li+ storage.


2015 ◽  
Vol 17 (40) ◽  
pp. 26864-26874 ◽  
Author(s):  
Debabrata Chanda ◽  
Jaromír Hnát ◽  
Ana S. Dobrota ◽  
Igor A. Pašti ◽  
Martin Paidar ◽  
...  

The RGO-modified Ni electrode exhibited outstanding activity towards HER. DFT calculations indicate that H atoms, formed upon H2O discharge on Ni, spill onto the RGO, enabling continuous clearance of Ni-active sites.


2016 ◽  
Vol 09 (05) ◽  
pp. 1650058 ◽  
Author(s):  
Huaping Wu ◽  
Ye Qiu ◽  
Junma Zhang ◽  
Guozhong Chai ◽  
Congda Lu ◽  
...  

The composites of sulphide and reduced graphene oxide (NiS/MoS2-rGO) were synthesized through a facile solvent-assisted hydrothermal method. The introduction of NiS was paramount not only in enhancing the conductivity of whole catalysts but also in modulating the layer structures of MoS2 with additional active sites. Moreover, the NiS and rGO functioned together in controlling the morphology of as-prepared composites, resulting in uniformly distributed NiS/MoS2 nanosheets perpendicular to rGO scaffold. This further contributed to the excellent hydrogen evolution performance of the composites with a small onset overpotential of 80[Formula: see text]mV and Tafel slope as low as 65[Formula: see text]mV/decade.


2014 ◽  
Vol 193 ◽  
pp. 692-700 ◽  
Author(s):  
Syed Muhammad Hafiz ◽  
Richard Ritikos ◽  
Thomas James Whitcher ◽  
Nadia Md. Razib ◽  
Daniel Chia Sheng Bien ◽  
...  

RSC Advances ◽  
2019 ◽  
Vol 9 (62) ◽  
pp. 36123-36135 ◽  
Author(s):  
Lemu Girma Beka ◽  
Xiangrui Bu ◽  
Xin Li ◽  
Xiaoli Wang ◽  
Chuanyu Han ◽  
...  

In this 2D NiCo-MOF/rGO hybrid, the MOF nanosheets provide abundant active sites while the conductive rGO provide rapid electron transport.


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