Hong He

Bio: Hong He is an academic researcher from Chinese Academy of Sciences. The author has contributed to research in topics: Catalysis & NOx. The author has an hindex of 76, co-authored 480 publications receiving 21717 citations. Previous affiliations of Hong He include University of Southern California & Saitama Institute of Technology.

Drivers of improved PM2.5 air quality in China from 2013 to 2017.

Abstract: From 2013 to 2017, with the implementation of the toughest-ever clean air policy in China, significant declines in fine particle (PM2.5) concentrations occurred nationwide. Here we estimate the drivers of the improved PM2.5 air quality and the associated health benefits in China from 2013 to 2017 based on a measure-specific integrated evaluation approach, which combines a bottom-up emission inventory, a chemical transport model, and epidemiological exposure-response functions. The estimated national population-weighted annual mean PM2.5 concentrations decreased from 61.8 (95%CI: 53.3-70.0) to 42.0 µg/m3 (95% CI: 35.7-48.6) in 5 y, with dominant contributions from anthropogenic emission abatements. Although interannual meteorological variations could significantly alter PM2.5 concentrations, the corresponding effects on the 5-y trends were relatively small. The measure-by-measure evaluation indicated that strengthening industrial emission standards (power plants and emission-intensive industrial sectors), upgrades on industrial boilers, phasing out outdated industrial capacities, and promoting clean fuels in the residential sector were major effective measures in reducing PM2.5 pollution and health burdens. These measures were estimated to contribute to 6.6- (95% CI: 5.9-7.1), 4.4- (95% CI: 3.8-4.9), 2.8- (95% CI: 2.5-3.0), and 2.2- (95% CI: 2.0-2.5) µg/m3 declines in the national PM2.5 concentration in 2017, respectively, and further reduced PM2.5-attributable excess deaths by 0.37 million (95% CI: 0.35-0.39), or 92% of the total avoided deaths. Our study confirms the effectiveness of China's recent clean air actions, and the measure-by-measure evaluation provides insights into future clean air policy making in China and in other developing and polluting countries.

Alkali‐Metal‐Promoted Pt/TiO2 Opens a More Efficient Pathway to Formaldehyde Oxidation at Ambient Temperatures

Abstract: Formaldehyde is emitted from building and furnishing materials and consumer products, and is known to cause irritation of eyes and respiratory tract, headache, pneumonia, and even cancer. It is a dominant indoor air pollutant, especially in developing countries, and significant efforts have gone into indoor HCHO purification to meet environmental regulations and human health needs. Removal of HCHO by adsorbents has been investigated extensively using potassium permanganate, activated carbon, aluminum oxide, and some ceramic materials. Sorbent effectiveness is typically limited by low adsorption capacities. Catalytic oxidation is the most effective technology for volatile organic compound (VOC) abatement because VOCs can be oxidized to CO2 over certain catalysts at much lower temperatures than in thermal oxidation. Supported noble metal catalysts (Pt, Pd, Rh, Au, Ag) or metal oxide catalysts (Ni, Cu, Cr, Mn) have been used for the catalytic oxidation of VOCs. Complete oxidation of HCHO over catalysts occurs above 150 8C on clean and oxidized films of Ni, Pd, and Al and over silver–cerium composite oxide, above 100 8C over Ag/MnOx-CeO2 [18] and Au/CeO2, [19] and above 85 8C over Pd-Mn/Al2O3 [17] and Au/FeOx. As catalytic oxidation at even lower temperatures is desirable for indoor air purification, the development of a catalyst for total HCHOoxidation at room temperature is of great interest. In our recent study, 1% Pt/TiO2 catalyst was shown to be effective for HCHO oxidation at room temperature, achieving 100% conversion of d= 100 ppm HCHO to CO2 and H2O at a gas hourly space velocity (GHSV) of 50000 h . However, we also observed that this type catalyst is not as active as needed for practical applications, and deactivates with time-on-stream. Herein, we report a novel alkali-metal-promoted Pt/TiO2 catalyst for the ambient destruction of HCHO. We show that the addition of alkali-metal ions (such as Li, Na, and K) to Pt/TiO2 catalyst stabilized an atomically dispersed PtO(OH)x–alkali-metal species on the catalyst surface and also opened a new low-temperature reaction pathway, significantly promoting the activity for the HCHO oxidation by activating H2O and catalyzing the facile reaction between surface OH and formate species to total oxidation products. Figure 1a shows the HCHO conversion to CO2 as a function of temperature over the x% Na-1% Pt/TiO2 (x= 0, 1, and 2) samples at a GHSVof 120000 h 1 andHCHO inlet of d= 600 ppm. All gas streams were humidified to a RH of around 50%. Before each activity test, the samples were reduced in H2 at 300 8C for 30 min. The sodium-free catalyst had low activity for the HCHO oxidation reaction, with HCHO conversion being only about 19% at 15 8C. With 1% Na addition, the HCHO conversion reached 96% at 15 8C and 100% at 40 8C. With 2% Na addition, 100% HCHO conversion to CO2 and H2O was measured at 15 8C. The effect of Na addition on the surface reducibility was examined by H2 temperature-programmed reduction (TPR; Figure 1b). The amounts of H2 consumption were about the same over all the samples, but the addition of Na shifted the reduction peak to lower temperatures, that is, from 2 8C for 1% Pt/TiO2 to 6 8C for 1% Na-1% Pt/TiO2 and 11 8C for 2% Na-1% Pt/ TiO2. Thus, the sample reducibility correlates with the sample activity. The most active 2% Na-promoted sample had excellent stability as checked by long isothermal tests. For example, at a GHSV of 300000 h 1 and with the same other reaction conditions, approximately 80% HCHO conversion was maintained over a 72 h-long test (Figure 1a, inset). Li and K were equally effective promoters to Na and imparted the same high activity and stability to the Pt species (Supporting Information, Figure S1). Water vapor and oxygen effects on the activity of Na-Pt/TiO2 are important (Supporting Information, Figures S2,S3). Deionized-water washing of the samples was performed to check the alkali-metal and Pt interaction.While most of the Na was removed from the Nacontaining catalysts, a residual amount remained (Supporting Information, Table S1). Activity test results (Supporting Information, Figure S1) showed that the washed catalyst had identical activity for HCHO [*] C. Zhang, F. Liu, Y. Liu, Prof. H. He Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Shuangqing Road 18, Beijing, 100085 (China) E-mail: honghe@rcees.ac.cn

Effect of manganese substitution on the structure and activity of iron titanate catalyst for the selective catalytic reduction of NO with NH3

Abstract: Selective catalytic reduction (SCR) of NO with NH3 over manganese substituted iron titanate catalysts was fully studied. The low temperature SCR activity was greatly enhanced when partial Fe was substituted by Mn, although the N-2 selectivity showed some decrease to a certain extent. The Mn substitution amounts showed obvious influence on the catalyst structure, redox behavior and NH3/NOx adsorption ability of the catalysts. Among FeaMn1-aTiOx (a = 1, 0.75, 0.5, 0.2, 0) serial catalysts, Fe0.5Mn0.5TiOx with the molar ratio of Fe:Mn = 1: 1 showed the highest SCR activity, because the interaction of iron, manganese and titanium species in this catalyst led to the largest surface area and the highest porosity, the severest structural distortion and most appropriate structural disorder, the enhanced oxidative ability of manganese species, the highest mobility of lattice oxygen, the proper ratio of Bronsted acid sites and Lewis acid sites together with the enhanced NOx adsorption capacity. (C) 2009 Elsevier B.V. All rights reserved.

A superior Ce-W-Ti mixed oxide catalyst for the selective catalytic reduction of NOx with NH3

Abstract: A superior Ce-W-Ti mixed oxide catalyst prepared by a facile homogeneous precipitation method showed excellent NH3-SCR activity and 100% N2 selectivity with broad operation temperature window and extremely high resistance to space velocity, which is a very promising catalyst for NOx abatement from diesel engine exhaust. The excellent catalytic performance is associated with the highly dispersed active Ce and promotive W species on TiO2. The introduction of W species could increase the amount of active sites, oxygen vacancies, and Bronsted and Lewis acid sites over the catalyst, which is also beneficial to improve the low temperature activity by facilitating “fast SCR” reaction and enhance both of the high temperature activity and N2 selectivity simultaneously by inhibiting the unselective oxidation of NH3 at high temperatures.

Plasmon-Induced Photodegradation of Toxic Pollutants with Ag−AgI/Al2O3 under Visible-Light Irradiation

Abstract: A plasmonic photocatalyst Ag−AgI supported on mesoporous alumina (Ag−AgI/Al2O3) was prepared by deposition−precipitation and photoreduction methods. The catalyst showed high and stable photocatalytic activity for the degradation and mineralization of toxic persistent organic pollutants, as demonstrated with 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP), and trichlorophenol (TCP) under visible light or simulated solar light irradiation. On the basis of electron spin resonance, cyclic voltammetry analyses under a variety of experimental conditions, two electron transfer processes were verified from the excited Ag NPs to AgI and from 2-CP to the Ag NPs, and the main active species of O2•− and excited h+ on Ag NPs were involved in the photoreaction system of Ag−AgI/Al2O3. A plasmon-induced photocatalytic mechanism was proposed. Accordingly, the plasmon-induced electron transfer processes elucidated the photostability of Ag−AgI/Al2O3. This finding indicates that the high photosensitivity of noble metal N...

Phd by thesis

Abstract: Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Graphitic Carbon Nitride (g-C3N4)-Based Photocatalysts for Artificial Photosynthesis and Environmental Remediation: Are We a Step Closer To Achieving Sustainability?

Abstract: As a fascinating conjugated polymer, graphitic carbon nitride (g-C3N4) has become a new research hotspot and drawn broad interdisciplinary attention as a metal-free and visible-light-responsive photocatalyst in the arena of solar energy conversion and environmental remediation. This is due to its appealing electronic band structure, high physicochemical stability, and “earth-abundant” nature. This critical review summarizes a panorama of the latest progress related to the design and construction of pristine g-C3N4 and g-C3N4-based nanocomposites, including (1) nanoarchitecture design of bare g-C3N4, such as hard and soft templating approaches, supramolecular preorganization assembly, exfoliation, and template-free synthesis routes, (2) functionalization of g-C3N4 at an atomic level (elemental doping) and molecular level (copolymerization), and (3) modification of g-C3N4 with well-matched energy levels of another semiconductor or a metal as a cocatalyst to form heterojunction nanostructures. The constructi...

Plasmonic-metal nanostructures for efficient conversion of solar to chemical energy

Abstract: Recent years have seen a renewed interest in the harvesting and conversion of solar energy. Among various technologies, the direct conversion of solar to chemical energy using photocatalysts has received significant attention. Although heterogeneous photocatalysts are almost exclusively semiconductors, it has been demonstrated recently that plasmonic nanostructures of noble metals (mainly silver and gold) also show significant promise. Here we review recent progress in using plasmonic metallic nanostructures in the field of photocatalysis. We focus on plasmon-enhanced water splitting on composite photocatalysts containing semiconductor and plasmonic-metal building blocks, and recently reported plasmon-mediated photocatalytic reactions on plasmonic nanostructures of noble metals. We also discuss the areas where major advancements are needed to move the field of plasmon-mediated photocatalysis forward.

Single-atom catalysts: a new frontier in heterogeneous catalysis.

Abstract: Supported metal nanostructures are the most widely used type of heterogeneous catalyst in industrial processes. The size of metal particles is a key factor in determining the performance of such catalysts. In particular, because low-coordinated metal atoms often function as the catalytically active sites, the specific activity per metal atom usually increases with decreasing size of the metal particles. However, the surface free energy of metals increases significantly with decreasing particle size, promoting aggregation of small clusters. Using an appropriate support material that strongly interacts with the metal species prevents this aggregation, creating stable, finely dispersed metal clusters with a high catalytic activity, an approach industry has used for a long time. Nevertheless, practical supported metal catalysts are inhomogeneous and usually consist of a mixture of sizes from nanoparticles to subnanometer clusters. Such heterogeneity not only reduces the metal atom efficiency but also frequent...