Conversion of the greenhouse gas carbon dioxide (CO2) to value-added products is an important challenge for sustainable energy research, and nanomaterials offer a broad class of heterogeneous catalysts for such transformations. Here we report a molecular surface functionalization approach to tuning gold nanoparticle (Au NP) electrocatalysts for reduction of CO2 to CO. The N-heterocyclic (NHC) carbene-functionalized Au NP catalyst exhibits improved faradaic efficiency (FE = 83%) for reduction of CO2 to CO in water at neutral pH at an overpotential of 0.46 V with a 7.6-fold increase in current density compared to that of the parent Au NP (FE = 53%). Tafel plots of the NHC carbene-functionalized Au NP (72 mV/decade) vs parent Au NP (138 mV/decade) systems further show that the molecular ligand influences mechanistic pathways for CO2 reduction. The results establish molecular surface functionalization as a complementary approach to size, shape, composition, and defect control for nanoparticle catalyst design.

The synthesis of ultrasmall supported bimetallic nanoparticles (between 1 and 3 nanometers in diameter) with well-defined stoichiometry and intimacy between constituent metals remains a substantial challenge. We synthesized 10 different supported bimetallic nanoparticles via surface inorganometallic chemistry by decomposing and reducing surface-adsorbed heterometallic double complex salts, which are readily obtained upon sequential adsorption of target cations and anions on a silica substrate. For example, adsorption of tetraamminepalladium(II) [Pd(NH3)42+] followed by adsorption of tetrachloroplatinate [PtCl42−] was used to form palladium-platinum (Pd-Pt) nanoparticles. These supported bimetallic nanoparticles show enhanced catalytic performance in acetylene selective hydrogenation, which clearly demonstrates a synergistic effect between constituent metals.

The sluggish hydrogen oxidation reaction (HOR) under alkaline conditions has hindered the commercialization of hydroxide-exchange membrane hydrogen fuel cells.Alowcost Ni/NiO/C catalyst with abundant Ni/NiO interfacial sites was developed as acompetent HOR electrocatalyst in alkaline media. Ni/NiO/C exhibits an HOR activity one order of magnitude higher than that of its parent Ni/C counterpart. Moreover,N i/NiO/C also shows better stability and CO tolerance than commercial Pt/C in alkaline media, which renders it av ery promising HOR electrocatalyst for hydrogen fuel cell applications.D ensity functional theory (DFT) calculations were also performed to shed light on the enhanced HOR performance of Ni/NiO/C;the DFT results indicate that both hydrogen and hydroxideachieveoptimal binding energies at the Ni/NiO interface,resulting from the balanced electronic and oxophilic effects at the Ni/NiO interface.Along with the rapid progress in the generation of clean hydrogen from water with renewable energy sources such as solar and wind energies,i ncreasing attention has been devoted to the efficient utilization of hydrogen directly as agreen fuel, in that the sole product of hydrogen combustion is water. Within this context, the hydrogen fuel cell is one of the most promising technologies for hydrogen utilization. [1] Even though commercial hydrogen fuel cells employing proton exchange membranes exhibit high power output, [2]