{"id":6391,"date":"2025-08-18T09:40:23","date_gmt":"2025-08-18T07:40:23","guid":{"rendered":"https:\/\/akki.ut.ee\/?p=6391"},"modified":"2025-08-18T09:43:17","modified_gmt":"2025-08-18T07:43:17","slug":"unified-ph-phabs-measurements-support-electrocatalysis-research","status":"publish","type":"post","link":"https:\/\/akki.ut.ee\/en\/unified-ph-phabs-measurements-support-electrocatalysis-research\/","title":{"rendered":"Unified pH (pHabs) measurements support electrocatalysis research!"},"content":{"rendered":"
\"\"<\/a>

Jaan Saame<\/p><\/div>\n

\"\"<\/a>

Agnes Heering<\/p><\/div>\n

In a recent publication Universal Reversible Hydrogen Potential for Electrocatalytic Ammonia Splitting Reactions in Nonaqueous Solvents from Unified pH Measurements. Inorg. Chem.<\/em> 2025<\/strong>, https:\/\/doi.org\/10.1021\/acs.inorgchem.5c02177<\/a>, jointly with colleagues from Michigan State University, we have used careful pHabs<\/sub> measurements of dilute NH4<\/sub>+<\/sup>\/NH3 buffer solutions in four nonaqueous solvents<\/strong> \u2013 acetonitrile (MeCN), Tetrahydrofuran (THF), dimethylformamide (DMF), and propylene carbonate (PC) \u2013 to determine the pHabs<\/sub>H2O<\/sup> values aligned to the aqueous pH scale (see the resulting pHabs<\/sub> “ladder” in the graph below). From those measurements (combined with some other experiments) it was possible to determine the reversible hydrogen potential E<\/em><\/strong>\u00b0H+\/H2<\/sub> in these four solvents <\/strong>relative to the aqueous standard hydrogen electrode (SHE) and, most importantly, ensuring comparability across the different solvents<\/strong>. As an independent method, Open Circuit Potential measurements were carried out in the same solvents titrated with NH4<\/sub>+<\/sup>\/NH3<\/sub> to obtain alternative values for the reversible hydrogen potential in these solvents. The results of the two methods agreed well.<\/p>\n

\"\"<\/a>The reversible hydrogen potential values were then used to obtain, for the first time, the overpotential for ammonia oxidation as a function of solvent<\/strong>, with a recently discovered ruthenium catalyst. I.e., it is now for the first time possible to rigorously compare the oxidation process of NH3<\/sub> to N2<\/sub> between different solvents!<\/strong><\/span><\/p>\n

This work is a clear demonstration of the usefulness of the unified pH (pHabs<\/sub>) concept<\/strong> in understanding and modelling electrocatalysis processes!<\/p>\n

Many thanks,<\/span> Jaan for performing the extremely difficult pHabs<\/sub>\u00a0measurements<\/span>,\u00a0<\/span>Agnes for leading this pHabs<\/sub>\/electrocatalysis topic in our group<\/span> and Michigan colleagues for the great collaboration<\/span>!<\/p>\n

All the experimental work at Tartu was carried out using the instrumentation of the AKKI (ECAC) infrastructure.<\/p>\n","protected":false},"excerpt":{"rendered":"

In a recent publication Universal Reversible Hydrogen Potential for Electrocatalytic Ammonia Splitting Reactions in Nonaqueous Solvents from Unified pH Measurements. Inorg. Chem. 2025, https:\/\/doi.org\/10.1021\/acs.inorgchem.5c02177, jointly with colleagues from Michigan State…<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[54],"tags":[],"class_list":{"0":"post-6391","1":"post","2":"type-post","3":"status-publish","4":"format-standard","6":"category-news"},"_links":{"self":[{"href":"https:\/\/akki.ut.ee\/en\/wp-json\/wp\/v2\/posts\/6391","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/akki.ut.ee\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/akki.ut.ee\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/akki.ut.ee\/en\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/akki.ut.ee\/en\/wp-json\/wp\/v2\/comments?post=6391"}],"version-history":[{"count":2,"href":"https:\/\/akki.ut.ee\/en\/wp-json\/wp\/v2\/posts\/6391\/revisions"}],"predecessor-version":[{"id":6394,"href":"https:\/\/akki.ut.ee\/en\/wp-json\/wp\/v2\/posts\/6391\/revisions\/6394"}],"wp:attachment":[{"href":"https:\/\/akki.ut.ee\/en\/wp-json\/wp\/v2\/media?parent=6391"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/akki.ut.ee\/en\/wp-json\/wp\/v2\/categories?post=6391"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/akki.ut.ee\/en\/wp-json\/wp\/v2\/tags?post=6391"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}