The development of active and durable bifunctional electrocatalysts for overall water splitting is mandatory for renewable energy conversion. This study reports a general method for controllable synthesis of a class of IrM (M = Co, Ni, CoNi) multimetallic porous hollow nanocrystals (PHNCs), through etching Ir-based, multimetallic, solid nanocrystals using Fe ions, as catalysts for boosting overall water splitting. The Ir-based multimetallic PHNCs show transition-metal-dependent bifunctional electrocatalytic activities for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in acidic electrolyte, with IrCo and IrCoNi PHNCs being the best for HER and OER, respectively. First-principles calculations reveal a ligand effect, induced by alloying Ir with 3d transition metals, can weaken the adsorption energy of oxygen intermediates, which is the key to realizing much-enhanced OER activity. The IrCoNi PHNCs are highly efficient in overall-water-splitting catalysis by showing a low cell voltage of only 1.56 V at a current density of 2 mA cm , and only 8 mV of polarization-curve shift after a 1000-cycle durability test in 0.5 m H SO solution. This work highlights a potentially powerful strategy toward the general synthesis of novel, multimetallic, PHNCs as highly active and durable bifunctional electrocatalysts for high-performance electrochemical overall-water-splitting devices.

The present study investigated the occurrence of 20 organophosphate esters (OPEs) in house dust from 51 South China homes and the risks of human exposure to OPEs via two pathways: dust ingestion and hand-to-mouth contact. In addition to several traditional OPEs, five out of six novel OPEs, including bisphenol A bis(deiphenyl phosphate) (BPA-BDPP), t-butylphenyl diphenyl phosphate (BPDPP), cresyl diphenyl phosphate (CDP), isodecyl diphenyl phosphate (IDDPP), and resorcinol-bis(diphenyl)phosphate (RDP), were frequently detected in house dust (median concentration: 59.7-531 ng/g). Eight of the 20 target OPEs were frequently detected in hand wipes collected from adults and children ( n = 51 and 31, respectively), which in combination (referred to as ΣOPEs) had a median mass of 76.9 and 58.9 ng, respectively. Increasing dust concentrations of ΣOPEs or three individual substances among these eight OPEs, including tris(1-chloro-2-propyl) phosphate (TCIPP), tris(1,3-dichloro-2-propyl) phosphate (TDCIPP), and triphenyl phosphate (TPHP), were strongly associated with their levels in children's hand wipes ( p < 0.05 in all cases). By contrast, in adults' hand wipes only TPHP exhibited a marginally significant association with dust concentrations ( p = 0.04). Levels of ΣOPEs in hand wipes from children, but not adults, were inversely influenced by hand washing frequency ( p = 0.002), while indoor temperature was inversely associated with hand wipe levels of ΣOPEs from both children and adults ( p = 0.01 and 0.002, respectively). Exposure estimation suggests that hand-to-mouth contact represents another important pathway in addition to dust ingestion and that children are subjected to higher OPE exposure than adults.

Emission characterization of polycyclic aromatic hydrocarbons (PAHs) from residential combustion of crop residues, woody material, coal, and biomass pellets in domestic stoves in rural China are compared in term of emission factors (EFs), influencing factors, composition profiles, isomer ratios and phase distributions. The EFs of PAHs vary by two orders of magnitude among fuel types suggesting that a detailed fuel categorization is useful in the development of an emission inventory and potential in emission abatement of PAHs by replacing dirty fuels with relatively cleaner ones. The influence of fuel moisture in biomass burning is non-linear. Biofuels with very low moisture display relatively high emissions as do fuels with very high moisture. Bituminous coals and brushwood yield relatively large fractions of high molecular PAHs. The emission factor of Benzo(a)pyrene equivalent quantity for raw bituminous coal is as high as 52 mg/kg, which is 1–2 orders of magnitude higher than the other fuels. For source diagnosis, high molecular weight isomers are more informative than low molecular weight ones and multiple ratios could be used together whenever possible.

Within the framework of Dyson-Schwinger equations , we discuss the chiral phase transition of QCD with a chiral chemical potential μ 5 as an additional scale. We focus especially on the issues related to the widely accepted as well as interesting critical end point (CEP). With the help of a scalar susceptibility, we find that there might be no CEP 5 in the T − μ 5 plane, and the phase transition in the T − μ 5 plane might be totally crossover when μ < 50 MeV, which has apparent consistency with the lattice QCD calculation. Our study may also provide some useful hints to some other studies related to μ 5 .