Today, R&D plays important roles in enhancing national competitiveness and sustainability. Many traditionally scientifically under-developed countries are now catching up and the global R&D landscape has seen dramatic changes. Facing the continuing competition, researchers, technology innovators, and policy makers all need to grasp the structure and developments of global research and innovation, so dynamical monitoring and dignosing of research fields become a strategic endeavor at higher levels of research planning and policy making.
Materials science is the foundation for many emerging industries. Graphene (Novoselovl et al., 2004), due to its outstanding electrical, thermal, and optical properties, has great potential for applications in energy, environment, electronics, biology and other fields. As a result, graphene research is gaining intensive attention world-wide. Many countries have embarked on R&D prgrams on graphene to position themselves among the leaders.
Scientometric analysis has recently been applied to map global trends of graphene research using publications or patent data. Evidence from such analysis shows that graphene research increased over past 20 years and saw an up-ward burst in recent 5 years (Lv et al., 2011). However, exponential growth in published articles has met with a decreasing average citation per article and diminishing share of highly-cited publications (Klincewicz, 2016; Zheng, 2016). Some attributed recent rising number of publications on graphene to the fact that researchers working in carbon nanotubes gradually move towards study of graphene (Etxebarria, Gomez-Uranga, & Barrutia, 2012). The growth complexity may also be due to graphene’s growing applications in non-electronics areas, such as health, environment, and energy (Klincewicz, 2016).
Some bibliometric analysis studies on global graphene research also included patent data. Researchers investigated graphane-related patents, with parameters like the time of application, the technology fields the patents belong to, applicants (Zhao & Chen, 2016), subjects, patentee’s technical strength, and Highly Cited Patents, to reveal the innovation trends (Zheng, 2016; Le & Polytechnic, 2017). A few papers compared the publications and patents on graphene to reveal the relationship between research and innovation (Peng, 2016). Still, a detailed and large scale analysis of graphene R&D is needed to fully reveal the landscape (Li, 2015).
The current paper uses publication data for research and patent data for innovation to study the trends of graphene R&D. Both types of data are provided by Chemical Abstracts Service (Perianes-Rodriguez, Waltman, & Eck, 2016; Retrieved from
CAplus database was searched for documents including “graphene” (case insensitive) in their subject or concept metadata, along with documents using the CAS Registry number for substance of graphene in CAS Registry. A set of 78,756 articles wereretrieved by April 5, 2016 for those published from 1985 to March 2016. Types of publications include journal articles, preprints, conference articles, dissertations, and books. 23,057 patents were obtained by April 5, 2016 for those applied from 1997 to March 2016. XML data files from CAS weremapped into an internal processing file format. Then, CAS indexing terms for topic, concept, substance, commercial or government entity, source of publication, and various other data entities, were extracted for analysis.
The investigations were conducted as follows:
Country/region distribution of publications and patents A global map was drawn to illustrate the numbers of patents and publications of each country/region, using the country/region of the first author affiliation as the basis. Top five producer countries were identified for both publications and patents. Then, for top 5 countries, the ratio of patents applied in other four countries to the total patents in each country was calculated, to demonstrate the patent flow in major countries. Description of the leading organizations in R&D Based on the number of papers or patents, we selected the top 20 research institutions with each assigned accordingly as university, research institute, or enterprise. In addition, we measured the year ranges that each organization has been active in research in graphene, and the percentage of output in the last three years to indicate the activeness of the institution. Moreover, using the concept indicators in publication metadata, we extracted the high-frequency concepts as top terms and high frequency concepts in last three years as recent terms, to demonstrate the hot research areas of the top 20 organizations. The IPC categories of patent applications are listed to show the technology area distribution in detail. Substaces and application roles distributions Substances are indexed for papers and patents by CAS, and the roles of substances are identified and divided into super roles and specific roles. This enables exploration of the substances role distribution in graphene research. For the specific roles, the distribution by year of the top 20 roles were analyzed; for the super roles, role evolutions from 2010 to 2016 were studied via three time slices, respectively 2010–2011, 2012–2013, and 2014–2016 where data for 2016 was incomplete. Because the role change was not obvious before 2009, data for 2008–2009 was added only for reference. Subject clustering of publications and patents Clustering of the publications and patents were conducted using the indexed concepts by CAS using the sofeware VOSviewer (Eck & Waltman, 2010, 2011). A visualized bibliometric network based on co-occurence (Eck & Waltman, 2009) was produced. Then, experts were invited to interpret the topics for each cluster. Furthermore, timelines were introduced to reveal the topics evolution. In addition, emerging terms, defined as those appering first time compared to all the early times, were detected for each of the periods of pre-2010, 2010–2011, 2012–2013, 2014–2016.
Figure 1 gives the overall growth of grapheme R&D. Publications or patents before 2000 were very limited, 336 and 2 respectively, so only data since 2000 were shown. The growth seemed very slow until the groundbreaking isolation of graphene for the first time in 2004 sparked a global explosion in graphene research. Both papers and patents started rapid increase since 2005, especially after 2010. Over 50 percent of papers and patents output were during 2014–2016, and the increase looks still strong, though some leveling-off may be ahead.
The country/region distribution of publications was produced as Figure 2. Those with total numbers of over 2000 are shown in red. Five top producers are China (excluding Hong Kong, Macao and Taiwan, similarly hereinafter), United States, South Korea, Japan and India. They together accounted for 64.3 percent of the global total. The distribution of patent applicant countries was also analyzed where the top five countries are China, South Korea, United States, Japan and Germany. They together accounted for over 90 percent of the global patents in graphene.
Figure 3 gives the relative outputs of the top five countries from 2000 to 2015. From the retrieved data, we know that the United States and Japan published their first papers in graphene in 1985 and 1992, respectively, and went strong until around 2010 when their publications began level-off and even began to decline after 2013. In contrast, publications from China has grown dramatically after 2010, surpassing the United States. The publications from South Korea overtook Japan since 2010, but increased only slowly afterwards, to be in similar strength as India in recent years. Nearly half of the publications from China and South Korea were produced during 2013–2015.
As for patent applications, data since 2001 were shown in Figure 4 for the top five countries identified in Figure 2. The United States and Japan applied their first patents in 1997 and 1999, respectively, but their applications began to drop considerably around 2008–2010. In contrast, the number of patents applied from China started since 2007 and increased dramatically ever since, with 2012 saw that China applied more than 50% of the world total, while the other four countries faced steady declination.
Figure 5 illustrates the flows of patent applications among the top five countries. The width of the arrows is proportional to the patent applications originated from one country to be applied in other countries. The majority of patent applications flew to United States and China. Although the total number of patent applications of China is high, only 2.3 percent of them are done in other countries. In contrast, the ratios that Korea, United States, Japan and Germany applied patents in other four countries are 27.8%, 24.8%, 32.3% and 45.3%, respectively. While Chinese institutes applied the largest number of patents, most were applied only in China.
Table 1 lists the top 20 organizations in terms of publications, 11 are in China, three in the United States, two in South Korea, two in Singapore, one each from Japan and Russia. 18 out of the 20 are universities, while the remaining two are research institutes, indicating that graphene research is dominated by universities and research institutes.
Top 20 organizations in graphene research papers.Organization Country Papers Type Years R Percentage (Last3 Years) Top Terms Recent Terms Chinese Academy of Sciences CN 2,973 Institute 1997–2016 45% Raman spectra; Nanocomposites; Surface structure Electrolytic polarization; Photothermal therapy; Mammary gland neoplasm University of California US 1,296 University 1994–2016 26% Band structure; Electric conductivity; Raman spectra Optical instruments; Thin film transistors; Ferroelectricity Nanyang Technological University SG 890 University 2001–2016 38% Raman spectra; Nanoparticles; Surface structure Transition metal; Encapsulation; Photoluminescence Tsinghua University CN 739 University 1998–2016 44% Raman spectra; Electric conductivity; Chemical vapor deposition Pore structure; Ion transport; Dielectric films Russian Academy of Sciences RU 738 Institute 1999–2016 38% Electric conductivity; Density of states; Band structure Lennard–Jones potential; Surface acoustic wave; Magnetocaloric effect National University of Singapore SG 712 University 2000–2016 30% Nanoribbons; Electric conductivity; Raman spectra; Flexibility; Permeability; Battery electrolytes The University of Texas US 672 University 2004–2016 25% Band structure; Electric conductivity; Field effect transistors Band offset; Melting point; Raman spectroscopy University of Science and Technology of China CN 616 University 2003–2016 41% Nanocomposites; Nanosheets; Electric conductivity Phase composition; Atomic layer deposition; Photocatalysts Peking University CN 563 University 1996–2016 44% Raman spectra; Chemical vapor deposition; Band structure Superconductivity; Semimetals; Cathodes Fudan University CN 516 University 1994–2016 43% Nanocomposites; Nanosheets; Nanoparticles Shubnikov-de Haas effect; Chronoamperometry; Crystal orientation Zhejiang University CN 509 University 1997–2016 55% Nanosheets; Raman spectra; Nanocomposites Open circuit potential; Adsorptive wastewater treatment; Heterojunction solar cells Nanjing University CN 468 University 2002–2016 46% Nanoparticles; Nanocomposites; Surface structure Crystal morphology; Drug delivery systems; Electrochemical analysis Massachusetts Institute of Technology US 458 University 1989–2016 30% Raman spectra; Chemical vapor deposition; Electric conductivity Thermoelectricity; Laser heating; Optical conductivity Sungkyunkwan University KR 446 University 2007–2016 50% Raman spectra; Chemical vapor deposition; Field effect transistors Double-layer capacitor electrodes; Aerogels; Aminoplasts Jilin University CN 414 University 2008–2016 49% Nanocomposites; Nanoparticles; Surface structure Lithium-ion secondary batteries; Thermal analysis; Contact angle Shanghai Jiao Tong University CN 397 University 2005–2016 52% Nanocomposites; Electric conductivity; Nanosheets Lithium-ion secondary batteries; Aerogels; Electrochemical reaction catalysts Seoul National University KR 392 University 2004–2016 49% Raman spectra; Surface structure; Electric conductivity Capacitors; Intercalation; Conducting polymers Tohoku University JP 370 University 1998–2016 26% Band structure; Electric conductivity; Fermi level Far–IR detectors; Grain size; Hot electrons Hunan University CN 368 University 2001–2016 61% Nanoparticles; Nanocomposites; Cyclic voltammetry Lithium-ion secondary batteries; Mid-IR spectra; Chemical potential Tianjin University CN 359 University 2003–2016 57% Nanoparticles; Raman spectra; Nanosheets Lithium-ion secondary batteries; Solar cells; Thickness
Major research topics for each of the top 20 were obtained using methods described in Section 2. It shows that Chinese organizations mainly focus on sensors, electronics and photovoltaics, and batteries, while US ones concentrated more on photoelectric properties, electronic structure, thin film transistors and semiconductors. Organizations from South Korea deal more on capacitors while the Japanes one focuses on electric properties.
20 top global graphene patent applicants are listed in Table 2. Among them, 14 were from China, four from South Korea and two from the United States. In addition, 15 assignees were universities or research institutes while the other five were enterprises.The top five were Chinese Academy of Sciences, Samsung Electronics, Ocean’s King Lighting Science & Technology, Zhejiang University, and LG Electronics. The major technology topics of patent applications for the top 20 organizations indicated that Chinese assignees applied patents more in preparation, batteries and composites, while the assignees from South Korea focused mainly in semiconductors devices and batteries and those from the United States primarily in semiconductors devices.
Top 20 applicants in graphene research papers.Organization Names Countries Patents Type Year Range Percentage (Last 3 Years) Top Terms Recent Terms Chinese Academy of Sciences CN 1,299 Institute 2007–2015 37% Fluoropolymers Chemical vapor deposition Films Three-dimensional printing Heat stabilizers Crystals Samsung Electronics Co., Ltd. KR 515 Enterprise 2007–2015 16% Electrodes Electroluminescent devices Semiconductor device fabrication Chalcogenides Binding energy Lithium primary batteries Ocean’s King Lighting Science & Technology Co., Ltd. CN 439 Enterprise 2010–2013 0% Composites Secondary batteries Fluoropolymers - Zhejiang University CN 270 University 2008–2015 49% Fluoropolymers Secondary batteries Nanocomposites Photoelectric cell electrodes Electric cables and wires Flexibility LG Electronics, Inc. KR 258 Enterprise 2009–2015 33% Secondary batteries Electroluminescent devices Fluoropolymers Aromatic hydrocarbons Polycyclic aromatic hydrocarbons Petroleum pitch Harbin Institute of Technology CN 222 University 2010–2015 61% Composites Fluoropolymers Secondary batteries Lithium-ion secondary batteries Aerogels Direct methanol fuel cells Tsinghua University CN 213 University 2009–2015 36% Secondary batteries Electrodes Fluoropolymers Cathodes Electron emission Fuel cell cathodes Shanghai Jiao Tong University CN 187 University 2009–2015 41% Composites Secondary batteries Fluoropolymers Electrolytic capacitors Electrolytes Paper International Business Machines Corporation US 186 Enterprise 2005–2015 11% Dielectric films Field effect transistors Semiconductor device fabrication Electrolytes Surface plasmon resonance Tunneling Korea Advanced Institute of Science and Technology KR 185 Institute 2008–2015 16% Nanowires Nanostructures Nanoparticles Distributed Bragg reflectors Energy storage systems Varistors Southeast University CN 154 University 2010–2015 44% Composites Heat treatment Nanoparticles Impregnation Injection molding Orthopedic prosthetics Jiangsu University CN 140 University 2010–2015 54% Nanocomposites Photolysis catalysts Nanoparticles Aerogels Double layer capacitors Electric capacitance University of Jinan CN 137 University 2010–2015 63% Antibodies and Immunoglobulins Immunosensors Blood serum albumins Magnetic separation Amination Prostate-specific antigen Beijing University of Chemical Technology CN 135 University 2009–2015 41% Styrene-butadiene rubber Natural rubber Nanoparticles Fireproofing agents ABS rubber Acrylic rubber Fudan University CN 133 University 2010–2015 48% Electrodes Composites Lithium-ion secondary batteries Lithium-ion secondary batteries Double layer capacitors Electrospinning University of Electronic Science and Technology of China CN 130 University 2010–2015 36% Coating process Films Polyesters Electric resistance Interference Optical modulators Shanghai University CN 129 University 2009–2015 62% Composites Fluoropolymers Secondary batteries Lithium-ion secondary batteries Aerogels Dispersion of materials Donghua University CN 120 University 2010–2015 48% Fluoropolymers Composites Polyoxyalkylenes Coupling agents Glass microspheres Pharmaceutical carriers Korea Institute of Science and Technology KR 117 Institute 2008–2015 21% Polyimides Solar cells Nanoparticles Enterobacteria phage M 13 Hydrogels Peptides Baker Hughes Inc. US 107 Enterprise 2008–2015 12% Nanoparticles Fullerenes Silsesquioxanes Crosslinking agents Ferrofluids Magnetic materials
The Discipline/Specialty Sections assigned by CAS to each indexed paper and patent were used to give an overview of the research areas of graphene. As shown in Figures 6, graphene R&D have scattered in many Sections such as Electric Phenomena, Electrochemical, Radiational, and Thermal Energy Technology, Optical, Electron, and Mass Spectroscopy and Other Related Properties, Surface Chemistry and Colloids, Ceramics, General Physical Chemistry, Biochemical Methods, Plastics Manufacture and Processing, Electrochemistry and Magnetic Phenomena. Of these, there is a gradual increase in R&D effort in Electrochemical, Radiational, and Thermal Energy Technology, Optical, Electron, and Mass Spectroscopy and Other Related Properties, Biochemical Methods, Plastics Manufacture and Processing, and Electrochemistry, as indicated by the percentage change of coverage in these areas over the years.
Analysis of technological areas was made using IPC (International Patent Classifications) data of the patents data, as shown in Figure 7. The highest concentrations are in graphene preparation, composites and batteries.
In 2013–2015, innovation in the following IPC categories are active: C08K0013/06 (Pretreated ingredients), C09D0007/12 (Other additives), H01M0010/0525 (Lithium batteries), and H01G0011/86 (Capacitors, specially adapted for electrodes), while the number of applications in the following IPC categories are relatively low: H01B0001/04 (Mainly consisting of carbon-silicon compounds, carbon, or silicon), and H01B0013/00 (Apparatus or processes specially adapted for manufacturing conductors or cables). The patents in the nanocomposites related IPC B82Y0030/00 (Nanotechnology for materials or surface science) and B82Y0040/00 (Manufacture or treatment of nanostructures) declined since 2012.
The evolution of graphene research topics was analyzed using the concepts of papers and patents indexed by CAS. Considering the dramatic increase after 2010, the data set was divided into two time windows, 1985–2009 and 2010–2016 (Figure 8 and 9, respectively). Two networks show that before 2009, graphene research mainly focused on the mechanical and other properties and electrical properties. But since 2010, it has extended continuously into a diverse range of potential applications, such as batteries, capacitors, semiconductors, and sensorsdevices.
Indexed concepts in papers and patents were analyzed to detect emerging concepts and their percentages among all the indexed terms, in four periods: before 2009, 2010–2011, 2012–2013, and 2014 and after, as in Figure 10. The sizes of the pie charts are proportional to the numbers of concepts and the orange color parts represent the percentages of emerging terms. Emerging concepts increased remarkably after 2010 and the trend correlated with widening of research and innovation into diverse fields, indicating the vitality of graphene R&D and potential for new break-throughs.
Substance roles indexed by CAS in the papers and patents were examined (Figure 11). 39.9 percent are USES, including TEM (Technical or Engineered Material Use), MOA (Modifier or Additive Use), CAT (Catalyst Use), NUU (Other Use, Unclassified); 20.8 percent are Special, including PRP (Properties) and NAN (Nanoscale Substances/Materials); 18.6 percent are PROC (Process), including PEP (Physical, Engineering or Chemical Process) and REM (Removal or Disposal).
Time distribution for substances roles was given in Figure 12. PRP (Properties) has declined since 2006; NAN (Nanoscale Substances/Materials), IMF (Industrial Manufacture), RGT (Reagent), CAT (Catalyst Use) have decreased since 2009; PEP (Physical, Engineering or Chemical Process) has remained constant since 2011; TEM (Technical or Engineered Material Use), ANT (Analyte), BSU (Biological Study, Unclassified), POF (Polymer in Formulation) have decreased since 2012. In contrast, BUU (Biological Use, Unclassified) has increased since 2008, MOA (Modifier or Additive Use), POL (Pollutant) and REM (Removal or Disposal) grew year on year. In general, the main roles declined recently while roles in Biological Use, Modifier or Additive Use, Pollutant, Removal or Disposal have become new focuses.
Time slice analysis was used to examine the evolution of emerging substance roles in graphene research (Figure 13). Based on the emerging substances, roles in USES and PROC (Process) have declined in recent years. On the contrary, the roles in PREP (Preparation) and BIOL (Biological Study) increased over time.
In summary:
In recent years, the numbers of both papers and patents in graphene continued their increases, indicating that R&D in graphene is still growing. China, United States, South Korea and Japan hold considerable technological advantages. United States and Japan developed their research and innovation earlier than China and South Korea, but China has become the largest R&D producer in recent years. Major Chinese graphene R&D actors are mainly universities and research institutes, while the R&D efforts in South Korea and the United States are dominated by enterprises. Chinese applications for patents concentrated mainly on preparation, batteries and composites, whereas South Korean organizations applied for patents mainly in semiconductor devices and batteries and US organizations did so primarily in semiconductor devices. The industrialized application of graphene materials is continuously expanding from mechanical, material, and electrical properties to a diverse range of potential applications such as batteries, capacitors, semiconductors, sensors, and semiconductors devices. The constant occurrences of the emerging terms in recent years also indicate a robust and diversifying R&D field. The roles of emerging substance roles tend to increase in Preparation and Biological Study over time, suggesting that the innovative application of graphene has caught the attention. And, it seems that the technology for preparing graphene materials will still be a major focus for the near future. Wide application of graphene in fields such as energy, biology, electronics and nano-composite materials, requires low-cost, green preparation processes, high-quality fine structure control and multilevel multifunctional assembly and integration. Development, improvement and optimization of preparation methods and techniques will be needed to maximize all the outstanding qualities of graphene.
In conclusion, graphene research and development has shown promising application potential across a wide range of fields, but challenges still exist in technological breakthrough in its preparation methods and processes in order to realize its industrialization for leading innovation in next-generation materials.