David King and his group developed the first calorimeter that could measure heats of adsorption on the well-defined surfaces of single crystals with sufficient precision to reveal new understanding of surface chemistry, especially by determining the energies of adsorbed molecular fragments that are catalytic reaction intermediates and otherwise inaccessible experimentally. Since then, our group and others have adopted this technique and made substantial extensions, including:<br/>(1) heat detector improvement, allowing routine measurements on single crystals from 100 to 350 K with high precision (a standard deviation of 1.3 kJ/mol with gas pulses that contain only 1% of a monolayer), (2) adsorption and adhesion energy measurements during the growth of thin films of metals and solvents, (3) measurements of the energetics of oxide-supported metal nanoparticles versus size on both single crystals and powdered catalyst support materials, (4) in situ measurements of the energetics of the elementary steps occurring during thin-film growth by atomic layer deposition (ALD), (5) measurements of electrochemical adsorption and reactions at liquid/solid interfaces, and (6) transient measurements of heat-signal line-shapes during two-step reaction mechanisms (e.g., molecular adsorption followed by dissociation) that give the heats for both steps and the rate constant for the second step during every gas pulse.<br/>These extensions and their applications will be reviewed to assess the current state of adsorption calorimetry on well-defined surfaces, and its future prospects.

Calorimetric methods in surface chemistry research

ACS Spring Meeting 2021

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