Abstract
Based on first-principles calculations at DFT level, we studied adsorbates-substrate interaction at surfaces in three different systems targeting low-dimensional materials fabrication and heterogeneous catalysis. On Au(111) surface, we fabricate and identify a two-dimensional gold-phosphorus network (AuPhoN), wherein blue phosphorene (blueP) subunits are linked by gold atoms. AuPhoN has a porous inorganic structure similar to the interesting organic networks whose tailorable architectures offer applications in sensing, catalysis, gas storage and topological phenomena. Evidence are provided showing that such metal-phosphorus networks are tunable in their chemical functionalities and electronic properties by simply altering the linkers and subunits. The epitaxial AuPhoN on Au(111) was mistakenly assigned in some previous works as the successful obtainment of monolayer blueP, a predicted rising allotrope of blackP that attracts extensive attentions. To access the so-far unrealized freestanding blueP, we propose a potential method through the transformation of blackP as induced by surface Br adsorption. Formation of extra Br-P bonds disrupts the original sp3 configurations in blackP, generates unpaired pz electrons, and causes a structural transformation that results in blueP formation. This result can be seen as a process that adsorbates “catalyze” the substrate into a desired product. The transformation from blackP to blueP however is not a conventional catalysis process. In heterogeneous catalysis, substrate activates adsorbates and lower the reaction barrier, where the Sabatier conflict limits the reaction rate. To resolve the Sabatier conflict, we find a new strategy for designing catalysts for the water-gas-shift reaction (CO + H2O → CO2 + H2). We avoid the conflicting tasks that require *OH or *O from dissociated water to adsorb on and then desorb from the substrate of a catalyst. Instead, the CO on metal directly obtains OH from water that are connected by weak hydrogen bonds to the substrate. Experimental and theoretical results show that bifunctional catalysts with weakly reactive substrates have significantly higher CO conversion rates.
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