Ternary Oxides of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:mi>s</mml:mi></mml:math>- and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:mi>p</mml:mi></mml:math>-Block Metals for Photocatalytic Solar-to-Hydrogen Conversion
Simon Gelin, Nicole E. Kirchner‐Hall, Rowan R. Katzbaer, Monica J. Theibault, Yihuang Xiong, Wayne Zhao, Mohammed M. Khan, Eric Andrewlavage, Paul Orbe, Steven M. Baksa, Matteo Cococcioni, Iurii Timrov, Quinn Campbell, Héctor D. Abruña, Raymond E. Schaak, Ismaïla Dabo
Abstract
Oxides containing metals or metalloids from the <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><a:mi>p</a:mi></a:math> block of the periodic table (e.g., <d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><d:mi>In</d:mi></d:math>, <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><g:mi>Sn</g:mi></g:math>, <j:math xmlns:j="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><j:mi>Sb</j:mi></j:math>, <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><m:mi>Pb</m:mi></m:math>, and <p:math xmlns:p="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><p:mi>Bi</p:mi></p:math>) are of technological interest as transparent conductors and light absorbers for solar-energy conversion due to the tunability of their electronic conductivity and optical absorption. Comparatively, these oxides have found limited applications in hydrogen photoelectrolysis, primarily due to their high electronegativity, which impedes electron transfer for reducing protons into hydrogen. We have shown recently that inserting <s:math xmlns:s="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><s:mi>s</s:mi></s:math>-block cations into <v:math xmlns:v="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><v:mi>p</v:mi></v:math>-block metal oxides is effective at lowering electronegativities while affording further control of band gaps. Here, we explain the origins of this dual tunability by demonstrating the mediator role of <y:math xmlns:y="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><y:mi>s</y:mi></y:math>-block cations in modulating orbital hybridization while not contributing to frontier electronic states. From this result, we carry out a comprehensive computational study of 109 ternary oxides of <bb:math xmlns:bb="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><bb:mi>s</bb:mi></bb:math>- and <eb:math xmlns:eb="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><eb:mi>p</eb:mi></eb:math>-block metal elements as candidate photocatalysts for solar hydrogen generation. We down-select the most desirable materials using band gaps and band edges obtained from Hubbard-corrected density-functional theory, with Hubbard parameters computed entirely from first principles, evaluate the stability of these oxides in aqueous conditions, and characterize experimentally four of the remaining materials, synthesized with high phase uniformity, to validate and further develop the computational models. We thus propose nine oxide semiconductors, including <hb:math xmlns:hb="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><hb:mrow><hb:mi>Cs</hb:mi><hb:mi>In</hb:mi></hb:mrow></hb:math><kb:math xmlns:kb="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><kb:msub><kb:mi/><kb:mn>3</kb:mn></kb:msub></kb:math><nb:math xmlns:nb="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><nb:mrow><nb:mrow><nb:mi mathvariant="normal">O</nb:mi></nb:mrow></nb:mrow></nb:math><rb:math xmlns:rb="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><rb:msub><rb:mi/><rb:mn>5</rb:mn></rb:msub></rb:math>, <ub:math xmlns:ub="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><ub:mi>Sr</ub:mi></ub:math><xb:math xmlns:xb="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><xb:msub><xb:mi/><xb:mn>2</xb:mn></xb:msub></xb:math><ac:math xmlns:ac="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><ac:mi>In</ac:mi></ac:math><dc:math xmlns:dc="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><dc:msub><dc:mi/><dc:mn>2</dc:mn></dc:msub></dc:math><gc:math xmlns:gc="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><gc:mrow><gc:mrow><gc:mi mathvariant="normal">O</gc:mi></gc:mrow></gc:mrow></gc:math><kc:math xmlns:kc="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><kc:msub><kc:mi/><kc:mn>5</kc:mn></kc:msub></kc:math>, and <nc:math xmlns:nc="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><nc:mi>KSbO</nc:mi></nc:math><qc:math xmlns:qc="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><qc:msub><qc:mi/><qc:mn>2</qc:mn></qc:msub></qc:math>, which, to the extent of our literature review, have not been previously considered as water-splitting photocatalysts. Published by the American Physical Society 2024