There's no formal ACS style for citing Creative Commons images. What's important is 1) that the image is covered by a CC license, and 2) that you include the attribution with the image to give credit to the creator. If the image is from an open access article published under a creative commons license, then you'll want include the article reference in your citations. You also want to note which CC license was used for the image.
Please email me (firstname.lastname@example.org) if you have specific questions about citing an image.
Here's one possible way to cite an open access journal article. The reference number should correspond to your reference list at the end of your essay.
Figure 1. Figure title, by Author(s), is licensed under CC BY-NC-ND 3.0 (Reprinted from ref. ##).
If it's from a website like Flickr, rather than an article. You would then reference the website where you found the image.
Figure 1. Figure title (URL) by Author(s) is licensed under CC BY 2.0. (Reprinted from ref. ##).
While you are not required to include an attribution for a public domain images, it's still a good idea to give credit (including an author if you can find one) if someone else wants to track that down that image.
Figure 1. Image Title (URL) by Author. Public domain. (Reprinted from ref. ##).
ACS style typically uses numeric in-text citations, typically superscript numbers in the order of the references appearing in your paper, like this.1 The references at the end of your paper are listed in the order in which they appear, with the numbers in parentheses like (1) and the journal titles abbreviated. There's an extensive list of these abbreviations in chapter 14 of the ACS Style Guide.
Some ACS journals do not require authors to include the article titles in the references. While you don't need the title to track down a copy of the article, it certainly helps you decide whether or not you want to check out the article. However, citing without the article title is helpful when space is limited, such as posters and presentation slides.
Here are some example citations; yours may vary slightly depending on what information you have for your reference. Please consult the ACS Style Guide on how to cite other types of sources like books in series or "early view" journal articles that don't yet have volume/page information. If you don't see anything in the guide that marches your resource exactly, you can usually adapt one or more of the existing examples (print newspaper + basic style for online resources to cite an online newspaper article).
|Journal article, article title included|
|(1) Quinn, P.K.; Collins, D.B.; Grassian, V.H.; Prather, K.A.; Bates, T.S. Chemistry and Related Properties of Freshly Emitted Sea Spray Aerosol. Chem. Rev. 2015, 115, 4383–4399.|
|Journal article, article title not included|
|(1) Daniel, K.B.; Callmann, C.E.; Gianneschi, N.C.; Cohen, S.M. Chem. Comm. 2016, 52, 2126-2128.|
|Newspaper/magazine article, online (C&EN is cited differently)|
| (1) Fikes, B.J. Computing Transforms Chemistry, Biotech. The San Diego Union-Tribune [Online], March 19, 2016. http://www.sandiegouniontribune.com/news/2016/mar/19/computers-chemistry-amaro-chen/ (accessed May 1, 2016).
(2) Bomgardner, M.M. Making Better Contact Lenses. Chem. Eng. News 2017, 95 (13), 29-33. https://cen.acs.org/articles/95/i13/Making-better-contact-lenses.html (accessed June 8, 2017).
|Book, no editor|
|(1) Sailor, M.J. Porous Silicon in Practice: Preparation, Characterization and Applications. Wiley VCH: Weinheim, Germany, 2012; pp 189-227.|
|(1) Wang, Y.; McCammon, J.A. Lipid Bilayers: Structure, Dynamics, and Interactions with Antimicrobial Peptides. In Molecular Modeling at the Atomic Scale: Methods and Applications in Quantitative Biology; Zhou, R. Eds.; CRC Press: Boca Raton, FL, 2015, pp 191-214.|
|Newspaper/magazine article from a full text database like Academic Search Complete|
|(1) Talbot, D.; Desalination out of Desperation. MIT Technology Review [Online], Jan-Feb 2015, pp 44-48. Academic Search Complete. http://search.ebscohost.com/login.aspx?direct=true&db=a9h&AN=100243720 (accessed May 1, 2016).|
|Online book, no editor, from a 3rd party aggregator like Ebrary|
|(1) Hill, R.H. Jr., Finster, D.C.; Laboratory Safety for Chemistry Students [Online]; Wiley: Hoboken, N.J., 2010; Chapter 5, pp 1-133. http://site.ebrary.com/lib/ucsd/reader.action?docID=10412641 (accessed May 1, 2016).|
|Online book, edited|
|(1) Leigh, B.S., Schlamadinger, D.E., Kim, J.E.; Talbot, D.; Structures and Dynamics of Proteins Probed by UV Resonance Raman Spectroscopy. In Biophysical Methods for Biotherapeutics: Discovery and Development Applications; Das, T.K. Ed.; John Wiley: Hoboken, NJ, 2014; pp 243-268. http://onlinelibrary.wiley.com/book/10.1002/9781118354698 (accessed May 1, 2016).|
|Online encyclopedia entry, with its own posting date and a DOI for the URL|
|(1) Valkó, P.; Hydraulic Fracturing. Kirk-Othmer Encyclopedia of Chemical Technology [Online]; Wiley & Sons, Posted April 29, 2014. http://dx.doi.org/10.1002/0471238961.hydrvalk.a01 (accessed May 1, 2016).|
|(1) U.S. Food & Drug Information. Is It a Cosmetic, a Drug, or Both? (Or Is It Soap?) http://www.fda.gov/Cosmetics/GuidanceRegulation/LawsRegulations/ucm074201.htm (accessed May 1, 2016).|