Applied Surface Science 356 (2015) 399–407 Contents lists available at ScienceDirect Applied Surface Science jou rn al h om ep age: www.elsevier.com/locate/apsusc Effect of titanium nitride coating on physical properties of three-dimensional graphene Fatemeh Dabir a , Rasoul Sarraf-Mamoory a,∗ , Manuela Loeblein b,c , Siu Hon Tsang c , Edwin Hang Tong Teo b a Materials Eng. Department, Tarbiat Modares University, 1411713116, Tehran, Iran b School of Electrical and Electronic Engineering, Nanyang Technological University, 639798, Singapore c CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, 637553, Singapore a r t i c l e i n f o Article history: Received 10 May 2015 Received in revised form 15 July 2015 Accepted 11 August 2015 Available online 13 August 2015 Keywords: Three-dimensional graphene Titanium nitride Ammonia Physical properties a b s t r a c t In this paper, titanium nitride (TiN) was applied on the surface and into the porous structure of three- dimensional graphene (3DG) by chemical method. This method consists of immersing 3DG into a solution containing Ti ions and annealing under ammonia atmosphere at 850 ◦ C. The effects of TiN coating and high temperature annealing under NH 3 on the physical properties of 3DG were investigated. For this purpose, the 3DG samples, with and without TiN coating, were characterized via XRD, SEM, XPS, and Raman spectroscopy. Then, the electrical resistivity, work function, and wettability of samples were determined by Van der Pauw method, contact angle meter, and UV photoelectron spectroscopy (UPS), respectively. The results showed that an almost pure and very crystalline TiN phase with titanium/nitrogen atomic ratio of 1.09 was formed on the 3DG network. Annealing of 3DG under NH 3 resulted in locally doping of graphene with nitrogen and generation of defects in its structure. After TiN coating, the work function value of 3DG (5 eV) was reduced to 4.68 eV, while its initial water contact angle decreased from 127 ◦ to 83 ◦ . © 2015 Published by Elsevier B.V. 1. Introduction Graphene (G), two-dimensional hexagonal arrangements of car- bon atoms, is at the forefront of materials research due to its unique physical, chemical, and mechanical properties [1]. The outstanding properties of graphene provide a wide range of potential applica- tions for graphene-based functional materials [2]. However, it is worth pointing out that the performance of these functional mate- rials is still lower than the expected data because of the restacking or aggregation of 2D graphene sheets owing to the strong van der Waals interactions between them [3]. Recently, a three-dimensional form of graphene (3DG) has been introduced as an ultra-light, very porous, conductive, and flexible interconnected network [4]. This unique structure of 3DG, while maintaining outstanding properties of two-dimensional graphene, has opened many applications for it such as in sensors [5], fuel cells ∗ Corresponding author. Tel.: +98 9121334979; fax: +98 2182884390. E-mail addresses: f.dabir@modares.ac.ir (F. Dabir), rsarrafm@modares.ac.ir (R. Sarraf-Mamoory), manuela001@e.ntu.edu.sg (M. Loeblein), shtsang@ntu.edu.sg (S.H. Tsang), htteo@ntu.edu.sg (E.H.T. Teo). [6], Li-batteries [7], and supercapacitors [8]. Moreover, the 3DG can be utilized as a scaffold for the growth of various nanomaterials in order to improve its own surface properties and expand the range of applications. There are some reports about the growth of differ- ent nanomaterials on 3DG, such as metal oxides [9,10], hydroxides [11], sulfides [12], noble metals [13], and polymers [14]. Never- theless, to the best of our knowledge, there are too few studies on decoration of 3DG with transition metal nitrides. Transition metal nitrides, such as TiN, are important functional materials in research and industrial fields because of their superior electrical conduc- tivity and high chemical stability [15]. In reports on TiN/graphene composites, so far the two-dimensional form of graphene has been used [16–19]. However, to this date, there is no study focused on the growth of TiN on the CVD-grown three-dimensional graphene networks. We expect that the TiN will increase the surface wettability of 3DG, while retaining its high electrical conductivity and chemical stability. Additionally, we also predict TiN to reduce the work func- tion of 3DG which affects the charge transport processes. Therefore, it is expected that the TiN/3DG composite creates new applica- tions in graphene field, because it combines superior properties of both 3DG and TiN. As a result, it is highly beneficial to evolve an http://dx.doi.org/10.1016/j.apsusc.2015.08.086 0169-4332/© 2015 Published by Elsevier B.V.