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The dry reforming of glycerol (GDR) is one of the alternatives for syngas production by utilizing biodiesel byproduct glycerol and CO 2. The development of highly active and stable catalyst is significantly important to achieve GDR process, and the current work provides insights into Co and Fe-doping effects of mesoporous CeO 2 (CoFeCe) catalysts synthesized by the colloidal solution combustion method. The prepared catalysts presented the uniform mesoporous structure, the doping of Co and Fe metals resulted in stronger metal-support interaction. The GDR experimental data were compared with the non-stoichiometric thermodynamic equilibrium values. The conversions of glycerol and CO 2 were increased with increasing the reaction temperatures due to the endothermic GDR reaction, and the H 2 /CO produced in syngas was in the range of 0.7–1.4. Due to the improvement of Co and Fe metals in the mesoporous structure of CeO 2 catalyst, the 7CoFeCe catalyst exhibited excellent and stable GDR performance and no significant signs of deactivation were observed during 76 h test, and the results indicated that the enhanced interaction and high dispersion of Co and Fe in mesoporous CeO 2 catalyst could inhibit carbon formation and promote GDR reaction. [Display omitted] • Co and Fe co-doping on CeO 2 catalyst enhanced GDR reactions. • Increasing in Co-doping improved conversions of glycerol and CO 2 to syngas. • Co–Fe interaction and CeO 2 redox ability inhibited the formation of carbon. • Catalyst with CoFeCe of mole ratio 7: 5:10 exhibited high activity and stability. [ABSTRACT FROM AUTHOR]

In this work, two different types of catalysts with MgO support for aqueous phase reforming of glycerol were prepared by the sol-gel method and calcining method, respectively, and the active metals (nickel or/and cobalt) were added by the initial wet impregnation (IWI) method. It is found that the catalyst supported by gelatinous MgO presents better dispersion and the amount of hydrogen produced by the catalyst containing gelatinous MgO support is more than 1.5 times compared with other catalysts. For the Ni–Co bimetallic catalysts, the higher reaction temperature is beneficial to hydrogen yield, but decreases hydrogen selectivity. A high concentration of glycerol increases hydrogen yield and selectivity. Introducing CaO as an absorbent in aqueous phase reforming can improve WGS reaction and reduce methanation reaction through in-situ CO 2 removal and capture. The gelatinous Ni–Co/MgO catalyst presents superior activity and multi-cycle stability. [Display omitted] [ABSTRACT FROM AUTHOR]

Chemical looping steam reforming (CLSR) of ethanol using oxygen carriers (OCs) for hydrogen production has been considered a highly efficient technology. In this study, NiO/MgAl 2 O 4 oxygen carriers (OCs) were employed for hydrogen production via CLSR with and without CaO sorbent for in-situ CO 2 removal (sorption enhanced chemical looping steam reforming, SE-CLSR). To find optimal reaction conditions of the CLSR process, including reforming temperatures, the catalyst mass, and the NiO loadings on hydrogen production performances were studied. The results reveal that the optimal temperature of OCs for hydrogen production is 650 °C. In addition, 96% hydrogen selectivity and a 'dead time' (the reduced time of OCs) less than 1 minute is obtained with the 1 g 20NiO/MgAl 2 O 4 catalysts. The superior catalytic activity of 20NiO/MgAl 2 O 4 is due to the maximal quantity of NiO loadings providing the most Ni active surface centers. High purity hydrogen is successfully produced via CLSR coupling with CaO sorbent in-situ CO 2 removal (SE-CLSR), and the breakthrough time of CaO is about 20 minutes under the condition that space velocity was 1.908 h−1. Stability CLSR experiments found that the hydrogen production and hydrogen selectivity decreased obviously from 207 mmol to 174 mmol and 95%–85% due to the inevitable OCs sintering and carbon deposition. Finally, stable hydrogen production with the purity of 89%∼87% and selectivity of 96%∼93% was obtained in the modified stability SE-CLSR experiments. [Display omitted] • High catalytic OCs were developed via the modified Pechi method. • 20NiO/MgAl 2 O 4 attained 96% H 2 selectivity and 1 minute 'dead time' in CLSR. • The breakthrough time of CaO was 20 minutes in SE-CLSR. • Stable H 2 yield with high purity was obtained in the long-term modified SE–CLR. [ABSTRACT FROM AUTHOR]

[Display omitted] • Integrated design of in-situ H 2 sorption/storage in WGS to H 2 production is proposed. • H 2 production from supercritical CO 2 , steam, air gasification of biomass is compared. • Energy analysis for H 2 production with in-situ H 2 sorption/storage is studied. The novel process on in-situ hydrogen sorption/storage during water gas shift (WGS) was proposed and the enhanced hydrogen production in supercritical CO 2 gasification (CG), air gasification (AG), and steam gasification (SG) from biomass was integrated. Pure hydrogen was obtained by regeneration from the material (Mg 2 Ni) used for in-situ H 2 absorption during WGS. The effects of temperature, pressure, steam-to-carbon (S/C) ratio, and the quantity of adsorbent for the enhanced hydrogen production with in-situ hydrogen sorption/storage were determined. When Mg 2 Ni was added as the in-situ H 2 adsorbent, the hydrogen conversion in WGS reaction was improved. The increase of temperature reduced the hydrogen yield. SG presented the highest hydrogen yield and AG showed the highest hydrogen conversion. The steam-to-carbon (S/C) had a positive effect on the hydrogen production for all the processes and the methanation reaction was greatly inhibited by AG. The energy efficiencies reached 22.98 %, 26.31 %, and 27.149.51 %, and the exergy efficiencies reached 61.66 %, 64.19 %, and 83.62 %, for CG, AG and SG, respectively. The system energy can be supplied by in-situ hydrogen sorption/storage and the energy requirement order was SG > CG > AG. [ABSTRACT FROM AUTHOR]

Under the high attention of the international community to CO 2 emissions, the capture utilization and storage (CCUS) and the CO 2 hydrogenation fuel production have become two popular directions, especially for the combination of the two processes. In this paper, the production of liquid fuels via the methanol synthesis pathway in an integrated CCUS system based on Aspen Plus models was studied. The NH 3 -CO 2 -H 2 O absorption was used to capture CO 2 and hydrogen was provided by water electrolysis using renewable energy sources. A two-stage reactor with a recirculating stream was specified for the process of CO 2 hydrogenation to synthesize methanol, and the liquid fuel dimethyl ether (DME) was reproduced by dehydrating methanol (Power-to-Liquid). The amount of absorbent used for the carbon capture process was determined and the yield differences due to the number of cycles in the intermediate methanol synthesis reaction were analyzed. It is possible to convert 4.15 t of CO 2 per tonne of DME produced at the mass material balance of the process. The optimization of the heat exchange network and the energy requirements for the total process were evaluated. It is calculated that the energy involved in producing 1 ton of DME in the process model is 176 GJ. The analysis of the overall process and the evaluation of models could provide options for the possibility of CCUS engineering application. [Display omitted] • An integral process model converts CO 2 to liquid fuels by methanol synthesis. • Treatment options are proposed for emissions that accumulate in the cycle of the process. • The model offers energy requirement assessment for possible engineering applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ni-based catalysts supported by mesoporous CeO 2 were successfully prepared for GDR. • Thermodynamic study of GDR was carried out to compare the experimental data. • 5Ni/CeO 2 presented the highest activity with glycerol conversion of 84.1% at 750℃. • Ni loading ratio of 5 could reduce the generation of filamentous carbon during GDR. In this paper, the mesoporous Ni/CeO 2 catalyst with high specific surface area was prepared by the colloidal solution combustion method and used for the production of syngas by glycerol dry reforming (GDR). The thermodynamic analysis was conducted by using a non-stoichiometric methodology based on the minimization of Gibbs's free energy. The characterization results show that the higher the Ni content, the weaker the interaction between Ni and the CeO 2 support. 5Ni/CeO 2 shows the most consistent Ni dispersion and uniform particle size, and it has the best catalytic activity in the GDR and the conversion of glycerol can reach 84.1 % at 750 °C. Besides, all catalysts exhibited excellent stability during the 10 h catalytic process. The temperature-programmed oxidation (TPO) results show that Ni loading ratio of 5 can reduce the production of filamentous carbon. Based on a kinetic model assuming a power law as a first-order reaction, the activation energy of the Ni-based catalyst for glycerol dry reforming was calculated. [ABSTRACT FROM AUTHOR]

[Display omitted] • SECLSR proposed realizes CO 2 in-situ capture & utilization to H 2 and syngas. • Conversion of CO 2 from in-situ extraction of dolomite using MDR at 850 °C is feasible. • NiO/NiAl 2 O 4 of 15% NiO presented good activity and stability in SECLSR and MDR. • The process is no need for separating catalyst and sorbent for SECLSR. Hydrogen production from chemical looping steam reforming using an oxygen transport catalyst is definitely enhanced by CO 2 in-situ capture, which shifts the chemical equilibrium and reduces the energy demands. The utilization of CO 2 from this process as a reactant for chemicals and fuels could help to improve economic reasons and mitigate its impact on climate. In this study, we proposed a sorption-enhanced chemical looping steam reforming of glycerol to realize the synergetic capture and conversion of CO 2 in one integrated chemical looping hydrogen production process. The process is characterized to use the oxidized NiO/NiAl 2 O 4 as a steam reforming catalyst, the reduced NiO/NiAl 2 O 4 as a CO 2 -CH 4 dry reforming catalyst, and the inexpensive dolomite as a CO 2 sorbent. The surface carbon that would deactivate the catalyst is combusted by air after CO 2 -CH 4 dry reforming and the Ni on the catalyst is re-oxidized. The coupling of these different processes of chemical looping steam reforming, CO 2 in-situ capture, dolomite decomposition and CO 2 in-situ utilization, results in simultaneous generation of high purity hydrogen and syngas. The results demonstrated that hydrogen of above 92.5% was one-step generated and CO 2 was decreased to zero in the pre-CO 2 breakthrough periods. The reduced NiO/NiAl 2 O 4 catalysts favored the CO 2 -CH 4 dry reforming at 850 °C. The syngas of H 2 -to-CO molar ratios of 0.8–1.1 through the conversion of CO 2 from in-situ extraction of the absorbed CO 2 dolomite, was produced. The NiO/Al 2 O 4 with 15 wt% NiO gave the highest hydrogen and syngas yields, and maintained high performance for the proposed system. The catalysts and dolomite exhibited good stability with no obvious loss of activity in 10 cycles. [ABSTRACT FROM AUTHOR]

Hydrogen production from sorption enhanced aqueous phase reforming (APR) of biodiesel byproduct glycerol was studied by Ni-based monometallic and bimetallic catalysts supported on gelatinous MgO supports. Compared with Ni-based monometallic catalyst, the H 2 selectivity and glycerol conversion of the Cu–Ni bimetallic catalyst were found to be increased more than 3% and 30%, respectively. Meanwhile, higher reaction temperature was found to have higher H 2 yield with lower H 2 selectivity. The H 2 yield using the catalyst with gelatinous MgO support was 1.25 times higher than that of calcined support. Through in-situ CO 2 capture, the addition of CaO to the Cu–Ni bimetallic catalyst increased more than 58.3% and 14.4% of the H 2 yield and selectivity, respectively. An analysis about liquid product component indicate that the presence of CaO promote the further cleavage of the C–C bond, which further increased the conversion of glycerol. Furthermore, it was found that the presence of CaO could also improve the stability of the catalyst through the control experiments. [Display omitted] • Sorption enhanced APR to H 2 with in-situ CO 2 capture was studied. • Monometallic and bimetallic supported on MgO were developed. • Cu–Ni supported on gelatinous MgO exhibited good APR performance. • H2 yield by gelatinous MgO support was 1.25 times higher than that of calcined MgO. • Presence of CaO in APR improved conversion, selectivity, and stability. [ABSTRACT FROM AUTHOR]

In this study, renewable hydrogen production was achieved by coupling of water splitting and glycerol oxidation reforming by chemical looping technology (CLWS-GOR) using the novel Ce–Ni modified Fe-based oxygen carriers (OCs). The OCs were developed by combining metal chelating sol-gel and isometric impregnation method, which exhibited anti-sintering characteristic and lattice oxygen migration ability in CLWS-GOR. The amount of hydrogen between 12.49 and 12.96 mmol in the steam stage was produced from all the OCs with different ratios of Fe, Ce and Ni. However, with the increase of Ce and Ni doping, the production of H 2 and CO in the fuel stage increased, as well as the probability of carbon deposits released in the subsequent steam stage. The H 2 /CO ratio in syngas were easily adjusted by steam to carbon molar ratio (S/C) in chemical looping steam reforming (CLSR), but the effects of steam introducing led to gradual deterioration of OCs. The results proved the OCs prepared by the combination method has high activity and stability for renewable hydrogen production from coupling of CLWS-GOR. [Display omitted] • Coupling of water splitting and glycerol oxidation reforming by chemical looping. • Ce–Ni modified Fe-based OCs were synthesized by combined method. • Pure H 2 was achieved from CLWS-GOR by reduced OCs. • WGS enhancement and the H 2 /CO ratio adjustment were achieved. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mesoporous Ni-Cu/CeO 2 was successfully synthesized to APR of biodiesel byproduct glycerol. • 1Ni2Cu/CeO 2 presented superior activity and multi-cycle stability in APR. • Cu element in catalysts effectively improved WGS and inhibited CH 4 formation. • Enhanced WGS and reduced methanation were achieved by in-situ CO 2 removal. Aqueous phase reforming (APR), regarded as one method for inexpensive H 2 production, was widely studied due to lower temperature and unnecessary to vaporize water and fuels. In this study, the mesoporous CeO 2 , regarded as a metal oxide carrier, was first prepared by colloidal solution combustion, and then the Ni-Cu bimetallic supported on mesoporous CeO 2 was successfully synthesized to investigate the catalytic performance in APR of biodiesel byproduct glycerol. The results show that the Cu element in the catalysts can effectively improve water–gas shift (WGS) reaction and inhibit the formation of methane, which increases the H 2 production rate from 125.08 to 195.57 µmol⋅min−1⋅g cat−1. The higher reaction temperature is beneficial to the H 2 production rate, but not to H 2 selectivity. Kinetics analysis indicates that catalyst of 1Ni2Cu/CeO 2 + 0.2gCaO has the lowest apparent activation energy (29.86 kJ⋅mol−1). CaO is introduced as an absorbent to improve WGS reaction and reduce methanation reactions through in-situ CO 2 removal and capture. The reaction path and mechanism of APR of glycerol are also discussed in this paper. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hydrogen was efficiently produced from CLSR of biodiesel byproduct glycerol. • Well-order mesoporous CeNiO/MCM-41 and CeNiO/SBA-15 were synthesized for CLSR. • High feeding conversion and H 2 selectivity was achieved by mesoporous OCs. • High loading NiO and CeO 2 on mesoporous OCs achieved excellent CLSR redox cycles. The selection of metal oxides and supports to improve catalytic activity and stability of oxygen carriers (OCs) is crucial for chemical looping steam reforming (CLSR) to hydrogen production. In this study, the Ni-based MCM-41 and SBA-15 OCs with and without CeO 2 promoter were prepared by direct synthesis and impregnation methods. The BET, XRD, TEM, ICP-AES, H 2 -TPR and DSC-TGA were used to analyze the synthesized OCs. Hydrogen production by CLSR using biodiesel byproduct glycerol was studied in a fixed-bed reactor with fuel and air stages. The DSC-TGA experiments were carried out to determine the thermal decomposition of biodiesel byproduct glycerol and the results indicated the exothermic and/or endothermic reactions as a result of secondary reactions and, the main degradation with the mass loss of 85.5 wt% occurred in the stages of 150–500 °C. The mesoporous OCs presented high specific surface area, large pore volume, and uniform pore size. It was found that the NiO and CeO 2 in the mesoporous OCs were first reduced by fuels and the reduced OCs was responsible of steam reforming and water gas shift (WGS) to hydrogen production, and hydrogen selectivity was up to 90% using CeNiO/SBA-15. The mesoporous OCs with Ce promoter greatly shortened 'dead time' (the reduce time of OCs), and effectively suppressed carbon deposited on OCs. High loading of NiO and CeO 2 on SBA-15 improved oxygen transfer and achieved excellent cyclic stability. These findings provide the fundamental understanding and principle of design on the conventional Ni-based OCs with room for further developments in chemical looping process. [ABSTRACT FROM AUTHOR]

The evaluation of thermochemical characteristics and the development of kinetic model for pyrolysis of waste biomass are more challenging. In this study, the mass losses, intermediates evolved and products formed during pyrolysis of waste wood biomass were determined by coupling DSC/TGA-DTG/GC-MS/FTIR to improve the understanding of conversion processes and decomposition characteristics. The improved non-isothermal kinetics method was proposed by introducing the function of mechanisms, the activation energies and pre-exponential factors were estimated iteratively by regression to enhance modeling accuracy. The results indicated the gases of CO, CO 2 , CH 4 , H 2 and the liquids of N-containing organics, esters, ketons and carboxylic acids were the most dominated products evolved. The pyrolysis of waste wood biomass could be divided into three phases, and with the increase of heating rates, the caloric requirement for pyrolysis was greatly increased. The random nucleation and one-dimensional diffusion predicted accurately the main (second) and third phases in the pyrolysis of waste wood biomass and waste camphor presented lower activation energies than waste bamboo. [Display omitted] • Pyrolysis of waste wood is studied by DSC/TG-DTG/GC-MS/FTIR. • Mass loss and energy requirement of pyrolysis are determined by DSC/TGA-DTG. • Gases and liquids of pyrolysis are analyzed by FTIR, GC-MS. • Improved kinetics method is derived to enhance the accuracy of model. [ABSTRACT FROM AUTHOR]

• A life cycle analysis on recycling and secondary use of lithium-ion batteries. • Based on the recycling in China, the LCA of different methods has been established. • Compared to other recovery, the secondary use has the lowest environmental impact. • Secondary use has the greatest impact on assessment results in dynamic situations. With the rapid development of the global new energy vehicle industry, how to minimize the environmental impact of the recovery has become a common concern and urgent concern. China is a major production and consumption market for electric vehicles, there are no specific and extensive resource and environmental assessment system for batteries. In this paper, the retired Electric vehicles lithium-ion batteries (LIBs) was the research object, and a specific analysis of the recycling treatment and gradual use stages of power batteries were based on life cycle assessment. Different battery assessment scenarios were established according to the development of battery recycling in China. The results showed that the secondary use has the optimal performance compared to the full-component physical, pyrometallurgical and hydrometallurgy recycling. The results showed that direct recycling has a GWP of 0.037 kg-CO 2 eq·kg LIB-1, which is lower than others. Secondary use of LIB accounts for the most emission reductions with Global warming (GWP) as 12.134 kg-CO 2 eq·kg LIB-1. The secondary use has the greatest impact on the assessment results, especially in dynamic scenarios. Through a comprehensive comparison of different recycling technologies, the secondary use, increasing the recycling rate, reducing resource, energy consumption and pollution emissions. [ABSTRACT FROM AUTHOR]

• The performance of a scroll compressor under two operating conditions was assessed. • The optimal OCR values for the two conditions were found to be 3.5% and 5.5% respectively. • Optimal air injection pressures on the two conditions were 0.27 and 0.45 Mpa respectively. • An empirical formula for the heating capacity as a function of vapor injection coefficient and OCR was derived. Heat pump air conditioning (AC) based on a vapor injection scroll compressor has proven to be a promising solution to the current driving range limitations of electric vehicles (EV), especially in freezing climates. The lubricating oil inside the compressor is critical in promoting sealing and cooling, but it also exhibits a low performance under extreme working conditions. In addition, the effects of oil retention on compressor behavior and the optimal charge amount at low temperatures require further investigation. This paper adapts a second refrigerant calorimeter method to study the effects of different injection pressures on compressor performance. The results indicate that the mass flow rate, discharge temperature, compressor power consumption, and volume efficiency performance would increase significantly compared with the non-vapor injection (NV). The effects of oil circulation rate (OCR) on the performance of a vapor injection scroll compressor under two low-temperature operating conditions were also studied. The flow and heat transfer parameters were analyzed, and heating capacity was found to increase and decrease with enlarged OCR. The highest coefficient of heating performance (COP) was obtained at an OCR of 3.5% with a vapor injection pressure of 0.28 MPa. Compared with the non-vapor injection (NV) condition, the heating capacity and COP of the system at the same pressure of 0.28 MPa were increased by 6.2% and 1.8%, respectively. At extremely low temperatures, the heating capacity and COP were maximized at an OCR of 5.5% and an injection pressure of 0.45 MPa. Compared with that of NV, the heating capacity and COP of the heating system at the injection pressure were increased by 6.7% and 2.6%, respectively. The compressor discharge temperature decreased obviously with the increasing OCR. An empirical formula was devised to calculate the heating capacity for varying OCR. [ABSTRACT FROM AUTHOR]

Photovoltaic (PV) power generation coupled with proton exchange membrane (PEM) water electrolysis favors improving the solar energy utilization and producing green hydrogen. But few systems proposed focus on achieving all-day stable hydrogen production, which is important for the future large-scale hydrogen utilization. Herein, a PV-Battery-PEM water electrolysis system for hydrogen production was constructed. An energy management strategy (EMS) was proposed to achieve the goal of all-day stable hydrogen production, improve energy utilization efficiency and reduce light discard rate. The PV power generation system, battery system and PEM electrolyzer for hydrogen production system were first established by Matlab/Simulink platform. Then, the overall PV-Battery-PEM electrolyzer system for hydrogen production was constructed, and the effectiveness of EMS was verified. The energy efficiency of the system under different working conditions with and without battery for energy storage was analyzed. The results show that the proposed energy management strategy can meet the purpose of all-day stable hydrogen production. Under the same working conditions, the energy efficiency of the system with battery for energy storage increases by 2–4% compared with the system without battery for energy storage, which indicates that the addition of energy storage can improve the energy utilization and reduce the light discarding. [Display omitted] [ABSTRACT FROM AUTHOR]

Biochar-assisted water electrolysis (BAWE) facilitates the high-value utilization of biomass and energy-saving hydrogen production. However, the BAWE efficiency is hindered by slow kinetics of biochar oxidation reaction (BOR) at anode. Herein, to improve the overall efficiency of BAWE, three-dimensional porous nanosheets modified on nickel foam (Ni 1 Fe 2 -LDH@NF) was developed for BOR, and its mechanism was identified. Impressively, the BAWE system exhibited remarkable activity, including a low potential of 1.387 V vs. RHE for BOR over as-synthesized electrocatalyst at current density of 10 mA·cm−2, and excellent long-term stability over 20 h at a high current density of 200 mA·cm−2 and after 1000 CV cycles. The required electricity input was 3.29 kWh·Nm−3H 2 at 10 mA·cm−2 for BAWE with Ni 1 Fe 2 -LDH@NF toward BOR. In addition, the reaction mechanism of BOR including biochar direct oxidation on the electrocatalysts surface and indirect oxidation in the electrolyte was deduced, according to the surface chemistry and composition changes of electrocatalysts and biochar, as well as the products. This work provides an effective strategy towards the enhancement of the BOR process by designing the binder-free electrocatalysts, and facilitates the development of BAWE for energy-efficient hydrogen production and biomass utilization. [Display omitted] • 3D porous Ni–Fe nanosheets modified on nickel foam was developed for enhancing BOR. • Ni 1 Fe 2 -LDH@NF favored the adsorption of OH− and accelerated the charge transfer rate. • Ni 1 Fe 2 -LDH@NF toward BOR demonstrated a potential of 1.387 V vs. RHE@10 mA·cm−2 and stability over 20 h@200 mA·cm−2. • The BOR mechanism including biochar direct oxidation on electrocatalysts and indirect oxidation in electrolyte was deduced. [ABSTRACT FROM AUTHOR]

Highly-efficient and stable non-noble metal electrocatalysts for overcoming the sluggish kinetics of oxygen evolution reaction (OER) is urgent for water electrolysis. Biomass-derived biochar has been considered as promising carbon material because of its advantages such as low-cost, renewable, simple preparation, rich structure, and easy to obtain heteroatom by in-situ doping. Herein, Ni 2 P–Fe 2 P bimetallic phosphide spherical nanocages encapsulated in N/P-doped pine needles biochar is prepared via a simple two-step pyrolysis method. Benefiting from the maximum synergistic effects of bimetallic phosphide and biochar, high conductivity of biochar encapsulation, highly exposed active sites of Ni 2 P–Fe 2 P spherical nanocages, rapid mass transfer in porous channels with large specific surface area, and the promotion in adsorption of reaction intermediates by high-level heteroatom doping, the (Ni 0.75 Fe 0.25) 2 P@NP/C demonstrates excellent OER activity with an overpotential of 250 mV and a Tafel slope of 48 mV/dec at 10 mA/cm2 in 1 M KOH. Also it exhibits a long-term durability in 10 h electrolysis and its activity even improves during the electrocatalytic process. The present work provides a favorable strategy for the inexpensive synthesis of biochar-based transition metal electrocatalysts toward OER, and improves the water electrolysis for hydrogen production. [Display omitted] • Ni 2 P–Fe 2 P spherical nanocages encapsulated in N/P-doped biochar is synthesized. • High-level heteroatom ((N + P + O): C) doping of 30.61 at% is achieved. • OER over (Ni 0.75 Fe 0.25) 2 P@NP/C demonstrates an overpotential of 250 mV@10 mA/cm2. • The synergistic effect of Ni 2 P–Fe 2 P and N/P-doped biochar promotes OER. [ABSTRACT FROM AUTHOR]

[Display omitted] • Au/Co-CC@iron ball shows superior photocatalytic activity, stability and reusability. • High property is due to synergy of active components and foliated iron ball surface. • Au/Co-CC@iron ball is used as packing material to construct packed reactor/module. • Via reactor/module, the removal of 4-NP is unprecedentedly enhanced to 2750 μmol/h. • Reactor/module has great potential in the continuous-flow degradation of 4-NP. Bulk noble metal–semiconductor composites can be chosen as photocatalysts to carry out the flow degradation of 4-nitrophenol (4-NP) whereas their preparation is complex and uncontrollable. Here, bulk Au-Co-CoO x -CeO x @iron ball (Au/Co-CC@iron ball) is designed and prepared by a facile and controllable route without any toxic chemical. The bulk Au/Co-CC@iron ball shows excellent photocatalytic activity and reusability for the 4-NP degradation, which can be ascribed to the synergistic action of active components and foliated iron ball surface. Furthermore, the highly active Au/Co-CC@iron ball is used as packing material to construct a new-type of packed reactor, by which the flow degradation of 4-NP is successfully achieved. As-fabricated packed reactor and its tandem module exhibit superior photocatalytic performance for the flow degradation of 4-NP. Noteworthy, based on the tandem module with six reactors, the removal rate of 4-NP can reach up to 2750 µmol/h. Meanwhile, the reactor and its module display satisfactory operational stability and reusability in the flow degradation of 4-NP. Clearly, the provided route is effective for the preparation of bulk noble metal–semiconductor composites with exceptional performance, which can also be a prospective strategy to obtain bulk packing materials to serve for the flow degradation. [ABSTRACT FROM AUTHOR]

• The mathematical model can accurately predict the melting heat transfer process of PCMs. • The Rayleigh number increased with the heat flux, and the higher the heat flux, the larger the amplitude. • Increasing the heat flux improved the integrated heat transfer coefficient and thermal storage performance of the CPCMs. • Conduction was the primary heat transfer mechanism; however, the proportion of natural convection increased with the heat flux. To investigate the effect of heat flux on the enhanced heat transfer in phase change materials (PCMs) composed of copper metal foam (CMF) and paraffin wax (PX), a semi-cylindrical visualized heat storage device with a varied heat flux of 7.3 kW/m2, 8.5 kW/m2, 9.7 kW/m2, and 10.9 kW/m2 was established in this paper. Moreover, a 3-D mathematical model of composite phase change materials (CPCMs) was established using hybrid grid to study the temperature distribution, imbalance effect, flow, heat transfer mechanisms, and heat storage performance during the melting process. The results showed that the melting time of the CPCMs decreased as the heat flux increased. Compared with a heat flux of 7.3 kW/m2, the melting time was shortened by 10.05 %, 20.71 %, and 27.21 %, respectively. In addition, the Rayleigh number (Ra) increased with the increase in heat flux, and the amplitudes of Ra were 1.45×108,1.54×108,1.61×108, and 1.74×108, respectively, which indicated that the higher the heat flux, the larger the amplitudes. Moreover, the heat transfer mechanism during the melting process was dominated by conduction; however, with the increase in heat flux, the maximum flow velocity of the liquid paraffin increased, which caused the proportion of natural convection to increase from 27.80 % to 31.30 %. Hence, the integrated heat transfer coefficient of CPCMs increased from 5.69 W/(m·K) to 5.81 W/(m·K). However, the temperature imbalance effect of the CPCMs was exacerbated, as evidenced by the increased maximum temperature difference in the vertical direction of the center of the CPCMs from 24.7 K to 35.6 K. Besides, the heat storage performance was enhanced. Compared with a heat flux of 7.3 kW/m2, the heat storage capacities of the CPCMs increased by 4.21%, 9.46%, and 12.66 % with increasing heat flux, and the heat storage rates of the CPCMs increased by 15.3 %, 34.9 %, and 52.3 %, respectively. Furthermore, the relative error of the overall melting time was 3.4 %, indicating that the model provided reasonable predictions. [ABSTRACT FROM AUTHOR]

• The addition of metal oxide particles greatly improves the thermal conductivity of MPCS. • MPCS with metal oxide particles can enhance heat transfer under different flow conditions. • Heating power and flow rates are crucial to the heat transfer of MPCS. • MPCS with metal oxide particles can be used as heat transfer medium and energy storage fluid. ZnO, nano ZnO and nano Al 2 O 3 were mixed with microencapsulated phase change material slurry (MPCS) for improving the heat transfer performance of slurries in this paper. The thermal and rheological properties of MPCS were measured using DSC, thermal conductivity meter and rheometer. The results show that the thermal conductivity of 5 wt% MPCS with 1 wt% ZnO, nano ZnO and nano Al 2 O 3 was 17.9 %, 19.4 % and 23.5 % higher than that of 5 wt% MPCS, respectively. The forced convection heat transfer experiment of slurries was carried out in a loop system with various heat flux and flow conditions. The influences of heat flux, flow rate and metal oxide particles on the flow and heat transfer behaviour of slurries were investigated. The results show that the heat transfer was significantly enhanced for all slurries with metal oxide particles under three flow conditions. Compared with water, the local heat transfer coefficient (h x) of MPCSs with 1 wt% ZnO, nano ZnO and nano Al 2 O 3 increased by 6.5 %, 9.1 % and 12.4 % under laminar flow, 6.6 %, 15.5 % and 14.9 % under transition flow, and 15.7 %, 19.0 % and 21.6 % in turbulent condition, respectively. [ABSTRACT FROM AUTHOR]

Semiconductors often have limited photocatalytic water-splitting performances owing to the narrow light absorption and low effective carrier density. In response to these challenges, we report the discovery of metallic amorphous cobalt boride (Co 2 B) as the first first-row transition metallic photocatalyst. It was prepared via a simple chemical reduction method and performs efficient water splitting spanning the UV, visible light and near-infrared region (NIR) via interband transitions. It achieves bifunctional water splitting activities with H 2 evolution rate of 202.3 μmol h−1 g−1 and O 2 evolution rate of 74.8 μmol h−1 g−1, superior to the existing (semi-)metallic photocatalysts. The material shows over 1 % apparent quantum efficiency (AQE) and 20 % incident photon to current conversion efficiencies (IPCE) at the NIR region >800 nm. Theoretical and photophysical experimental studies synergistically confirm that the metallic nature with high carrier concentrations and amorphous structure with abundant active sites contribute to the good water splitting performance of Co 2 B. This research sets the foundation for the utilization of highly efficient transition metal-based metallic photocatalysts in photocatalysis across the entire solar spectrum. [Display omitted] [ABSTRACT FROM AUTHOR]

Semiconductors often have limited photocatalytic water-splitting performances owing to the narrow light absorption and low effective carrier density. In response to these challenges, we report the discovery of metallic amorphous cobalt boride (Co 2 B) as the first first-row transition metallic photocatalyst. It was prepared via a simple chemical reduction method and performs efficient water splitting spanning the UV, visible light and near-infrared region (NIR) via interband transitions. It achieves bifunctional water splitting activities with H 2 evolution rate of 202.3 μmol h−1 g−1 and O 2 evolution rate of 74.8 μmol h−1 g−1, superior to the existing (semi-)metallic photocatalysts. The material shows over 1 % apparent quantum efficiency (AQE) and 20 % incident photon to current conversion efficiencies (IPCE) at the NIR region >800 nm. Theoretical and photophysical experimental studies synergistically confirm that the metallic nature with high carrier concentrations and amorphous structure with abundant active sites contribute to the good water splitting performance of Co 2 B. This research sets the foundation for the utilization of highly efficient transition metal-based metallic photocatalysts in photocatalysis across the entire solar spectrum. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Uniform submicro-sized cubes are covered on the copper wire surface by etching. • Etched copper wires are used as catalysts for the reduction of 4-nitrophenol. • Etched copper wires exhibit high catalytic activity, recyclability and stability. • Optimized etching provides a novel route to control the surface of metal materials. Up to now, the reported methods to regulate the surface morphology of metals are complicated and thus difficult to achieve. Herein, the etching method is optimized and used to change the surface morphology of copper (Cu) wire. By adjusting the amount of HCl as etching agent and the purity of Cu wire as the raw material, the Cu wire covered by uniform submicro-sized cubes (CWC) is successfully prepared and chosen as catalyst for the reduction of 4-nitrophenol. The CWC shows superior catalytic activity, recyclability and stability. Clearly, the as-provided etching method is effective for the surface morphology control of Cu wire, which can be a prospective strategy to obtain the metal materials with special surface morphology. [ABSTRACT FROM AUTHOR]

A novel sulfur–iodine (SI or IS) cycle integrated with HI–I 2 –H 2 O electrolysis for hydrogen production was developed and thermodynamically analyzed in this work. HI–I 2 –H 2 O electrolysis was used to replace the conventional concentration, distillation, and decomposition processes of HI, so as to simplify the flowsheet of SI cycle. And then the new cycle was divided into Bunsen reaction, H 2 SO 4 decomposition and HI–I 2 –H 2 O electrolysis sections. Through incorporating the user-defined module of HI–I 2 –H 2 O electrolysis with Aspen Plus, the cycle was simulated and 0.448 mol/h (10 L/h) of H 2 was produced. The overall energy and exergy efficiencies of the novel SI system were estimated to be 15.3–31.0% and 32.8%, respectively. Most exergy destruction occurred in the H 2 SO 4 decomposer and condenser for H 2 SO 4 decomposition and Bunsen reaction sections, which accounted for 93.0% and 63.4%, respectively. A high exergy efficiency of 92.4% for HI–I 2 –H 2 O electrolysis section with less exergy destruction was determined, mostly due to the transformation of the overall electricity in electrolytic cell to exergy. Appropriate internal heat exchange and waste heat recovery will favor improving the energy and exergy efficiencies. • A new SI cycle assembled with HI–I 2 –H 2 O electrolysis was thermodynamically analyzed. • Exergy destruction and exergy efficiency for each section were evaluated. • A high exergy efficiency of 92.4% for HI–I 2 –H 2 O electrolysis section was found. • The energy and exergy efficiencies of 15.3–31.0% and 32.8% were estimated for SI cycle. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electrochemical activation of biochar was achieved via limited electrooxidation. • Biochar-assisted water electrolysis reduced electricity consumption for hydrogen production. • Oxygen-containing groups enriched on biochar during its electrooxidation. • Upgraded biochar by electrochemical activation enhanced its removal of Cr(VI). • Cr(VI) removal mechanism by upgraded biochar follows attraction-reduction-complexation. Biochar-assisted water electrolysis (BAWE) has the potential to reduce the electricity consumption of hydrogen production. However, prolonged electrolysis leads to over-oxidation of biochar, reduced reactivity, and decreasing hydrogen production at cathode. Herein, we proposed the electrochemical activation of biochar via limited biochar oxidation reaction (BOR) and hydrogen evolution reaction (HER) in BAWE process, and the upgraded biochar was employed to remove Cr(VI). Distinct biochar was first pyrolyzed from three kinds of representative biomass components, cellulose, lignin, and their mixture at different temperatures. All of them exhibited excellent BOR activity, especially the biochar derived by the pyrolyzed cellulose and lignin at 800 °C (MBC-800) required a potential as low as 1.319 V vs. RHE@1 mA cm−2 using Pt electrode in 1 M KOH and achieved a Faraday efficiency almost 100% for hydrogen production. BAWE presented an energy-saving electrical consumption of 4.98 kWh Nm−3 H 2 compared to the conventional water electrolysis of 5.32 kWh Nm−3 H 2. Electrochemical oxidation enriched the oxygen-containing groups on biochar surface, which significantly improved its reductivity towards Cr(VI) and complexation with Cr(III), leading to the removal rate of Cr(VI) more than doubled. Results showed the achievement of electrochemical activation of biochar by limited electrooxidation. These findings provide a new route for the high-value utilization of biochar and energy-saving electrolytic hydrogen production. [ABSTRACT FROM AUTHOR]

SO 2 -depolarized electrolysis (SDE) is the key process in the hybrid sulfur cycle for green hydrogen production, but the detailed SDE characteristics including products generation, current efficiency variation, and side reactions are unclear. Herein, a continuous SDE process was experimentally conducted and theoretically modelled. The H 2 and H 2 SO 4 production was accelerated and the current efficiency for both electrodes was improved with a proper increase in current density (50−100 mA/cm2) or temperature (293−318 K), but further increasing current density to 150 mA/cm2 or temperature to 333 K led to a negative trend because of the anode corrosion or declined SO 2 solubility. The increasing initial H 2 SO 4 concentration (10−40 wt%) facilitated the cathodic H 2 production and current efficiency, while negatively influenced the anodic SO 2 conversion. The parasitic reactions occurred at cathode consumed H 2 and resulted to the cathodic current efficiency well below 100%. A rigorous mathematical regression model correlating the production rates of H 2 and H 2 SO 4 with current density, temperature, and initial H 2 SO 4 concentration was developed, and combined with the analysis of variance, current density was suggested the biggest factor affecting products generation in SDE process. These findings demonstrate a practical avenue for efficient SO 2 conversion and H 2 production in SDE process of hybrid sulfur cycle. [Display omitted] • H 2 and H 2 SO 4 production, current efficiency, and side reactions during SDE process were characterized. • Influence of current density, temperature, and initial H 2 SO 4 concentration on SDE process were emphasized. • Rigorous mathematical regression models concerning H 2 and H 2 SO 4 production rates were developed. • Current density was the biggest influencing factor toward products generation during SDE process. [ABSTRACT FROM AUTHOR]

Three nanoscale metal oxides composed of nano TiO 2 , nano Al 2 O 3 , and nano MgO were added to the phase change microcapsule slurry for optimising the heat transfer behaviour. The thermal and rheological properties of the resulting microencapsulated phase change materials (MPCMs) and microencapsulated phase change material slurries (MPCSs) were characterized to determine the effects of added metal oxides in optimising the performance of MPCSs. The impacts of factors like metal oxides, concentrations, and flow rates on the heat transfer behaviour of MPCSs were investigated by forced convective heat transfer experiment with various working conditions. Compared to 6 wt% MPCSs, the heat transfer coefficients (h x) of 6 wt% slurries containing 1 wt% TiO 2 , 1 wt% Al 2 O 3 , and 1 wt% MgO increased by 4.0 %, 2.5 %, and 7.13 %, respectively. Nano-MgO showed the most significant heat transfer enhancement effect on MPCSs. Moreover, the heat transfer performance gradually enhanced as a function of the concentration for nano MgO. Overall, the addition of metal oxides enhanced heat transfer by increasing the thermal conductivity of the slurry, as well as improved the micro-convection effect. The proposed MPCSs are promising for applications in solar photovoltaic/thermal (PV/T) systems, chip cooling, thermal management, buildings, and automotive cooling. [Display omitted] • Forced convection heat transfer experiment were conducted with bonded triangular tubes. • Heat transfer enhancement achieved by optimising heat transfer medium and tube structure. • Metal oxide type and concentration have significant effect on heat transfer of slurries. • Nano-MgO showed the most significant heat transfer enhancement effect on slurries. [ABSTRACT FROM AUTHOR]

• A flowsheet of SI cycle considering the Bunsen reaction kinetics was developed. • A user-defined Fortran module concerning Bunsen reaction kinetics was established. • Internal heat exchange network was created using pinch point temperature difference analysis. • The theoretical thermal efficiency of SI system was obtained in the range of 14.0–57.4 %. Thermochemical sulfur-iodine (SI) cycle is one of the large-scale, clean, and efficient hydrogen production routes. The Bunsen reaction process is always simulated by a stoichiometric reaction, without considering the realistic Bunsen reaction kinetic process. Herein, a user-defined Fortran module concerning Bunsen reaction kinetics was developed and embedded into a continuous stirred tank reactor (RCSTR), and then a SI flowsheet with 100 L/h hydrogen production was modeled. The key parameter optimization, mass and energy balance were analyzed, the internal heat exchange network was created using the pinch point temperature difference analysis and the principle of energy cascade utilization, along with thermal efficiency evaluation. Bunsen reaction process reaches equilibrium after a period, which is consistent with experiments. The increase of H 2 SO 4 decomposition ratio is beneficial to reduce the energy consumption of system. Increase in temperature has less effect on increasing the equilibrium decomposition ratio of HI. The theoretical thermal efficiency of system reaches 14.0–57.4 % considering the recovery of exothermic heat. This work provides a theoretical basis for the optimization of SI cycle. [ABSTRACT FROM AUTHOR]

• Condensation heat transfer and pressure drop were investigated experimentally with R410A and R32 in four different tubes. • The surface structures inside tubes were smooth, hydrophobic, herringbone and hydrophobic/herringbone, respectively. • The performance enhancement factor and specific sensitivity factor were used to evaluate the influence of overall heat transfer performance. An experimental investigation was performed to evaluate the condensation heat transfer characteristics for R32 and R410A inside four horizontal round tubes with 12.7 mm outer diameter. The saturation temperatures were 35 °C and 45 °C, the vapor qualities ranged from 0.2 to 0.8, and the mass flux ranged from 50 kg m−2 s−1 to 200 kg m−2 s−1. Different inside surface structures of the four tubes were smooth (ST), hydrophobic (HYD), herringbone (HB) and hydrophobic/herringbone (HYD/HB), respectively. Effects of mass flux, vapor quality, refrigerant and saturation temperature on condensation heat transfer in different tubes were discussed with the aid of flow pattern visualizations. Experimental results show that the heat transfer coefficient of R32 was higher than that of R410A due to different physical properties of the refrigerant. HB tube had the highest heat transfer coefficient at low vapor quality and HYD tube was the best at high vapor quality. The performance enhancement factors (PEF) of HB tube and HYD tube were better, ranging from 1.07 to 1.4 and from 1.02 to 1.31, respectively. However, as the composite of HB and HYD, the HYD/HB tube had the lowest overall performance, with the PEF ranged from 0.94 to 1.12. Additionally, the specific sensitivity factor (SSF) was used to evaluate the influence of various parameters on heat transfer and pressure drop. [ABSTRACT FROM AUTHOR]

A visual experimental system was built to explore the effect of low-pore-density copper metal foam (CMF) on the heat transfer during paraffin wax (PX) melting, and the effective thermal conductivities of composite phase change materials (PCMs) were obtained. A three-dimensional mathematical heat transfer model was established, the microstructure of the CMF was characterized using a high-definition camera, and a physical model of the CMF ball was determined. The melting heat transfer mechanism of the composite PCMs was investigated through the experimental and simulation results, including the temperature distribution, velocity vector, solid-liquid interface, volume fraction, heat transfer mechanism, and heat storage performance. The results show that as the CMF filling ratio increased from 0% to 2.13%, the temperature gradients of the composite PCMs were 86.1, 74.6, 29.2, and 12.6 K, indicating that the filling of CMF effectively alleviates the thermal stratification phenomenon during PX melting. Incorporation of the CMF increased the thermal conductivity of the composite PCMs, but suppressed their natural convection. When the CMF filling ratio was less than 1.28%, natural convection dominated the heat transfer type during PX melting; meanwhile, when the CMF filling ratio was greater than 1.28%, heat conduction was the major heat transfer mechanism. The composite PCMs exhibited great heat storage performance when the CMF filling ratio was 1.68%, and the heat storage rate was 13.25% higher than that of pure PX with the same heat storage capacity. In addition, a theoretical calculation model for predicting the heat transfer mechanism of the composite PCMs was established, and the results show that as the CMF filling ratio increased from 0.43% to 2.15%, the natural convection proportion of heat transfer performance decreased from 82.74% to 13.99% during the melting process. • The mathematical model can well predict the melting heat transfer process of PCMs. • The filling of CMF leads the paraffin temperature distribution more uniform. • Natural convection is dominated as the CMF filling ratio is less than 1.28%. • The composite PCM has better heat storage performance as CMF filling rate is 1.68%. [ABSTRACT FROM AUTHOR]

To explore the effect of metal foam(MF)pore density on the melting and heat transfer of phase-change materials(PCMs), a semi-cylindrical visualization experimental setup was established to experimentally study copper MFs with different pore densities coupled with paraffin wax. The results showed that as pore density increases, the melting time of the composite PCMs decreases compared to that of pure paraffin wax by 11.5%, 16.2% and 18.1% for pore densities of 5, 20, and 30 PPI, respectively. Composite PCMs with a pore density of 30 PPI exhibited fastest melting and lowest maximum temperature difference during melting. Considering the relative thermal energy storage(TES) capacity and relative TES rate, composite PCMs with a pore density of 30 PPI exhibited optimal overall thermal storage performance. Furthermore, heat conduction was the primary means of thermal transmission during the melting of the bottom paraffin. However, the melting of the upper paraffin was nevertheless influenced by natural convection, Hence, as pore size decreased, the influence on the weakening of natural convection became more significant. The results of the study provide guidance for the optimal design of latent heat storage devices for semi-cylinders. • The metal foam's pores are smaller the more effectively it transfers heat. • The copper foam with a 30 PPI pore density exhibited the best thermal storage performance. • The natural convection effect was less noticeable as pore size decreased. • The rate of heat storage increased as pore density continued to rise. [ABSTRACT FROM AUTHOR]

[Display omitted] • Correlation between biochar oxidation reaction (BOR) and electrolytes was determined. • Alkaline electrolyte was more favorable for biochar-assisted water electrolysis. • The higher concentration of H 2 SO 4 and S O 4 2 - slowed down the BOR kinetics. • The highest diffusion coefficient of 3.11 × 10−3 cm2∙s−1 for biochar was obtained at pH of 13.98. Biochar-assisted water electrolysis (BAWE) for hydrogen production is employed to reduce energy consumption by replacing the oxygen evolution reaction (OER) with thermodynamically more favorable biochar oxidation reaction (BOR). Electrolyte, as a carrier to dissolve the biochar particles and form conductive solution, is essential for the transfer and transformation of biochar particles and free radical precursors. Herein, the effects of electrolyte type, concentration, and pH on the BOR performance of BAWE system were investigated. Results show that 1 M KOH solution as an electrolyte was more suitable for the BAWE system, and the BOR of the alkaline BAWE system had the higher electrochemical activity (E 10 = 1.649 V vs RHE, 56 mV∙dec−1) compared with the OER in conventional water electrolysis system (E 10 = 1.982 V vs RHE, 189 mV∙dec−1). The anion adsorption phenomenon appeared in acidic media restricted the BOR kinetics. In addition, the diffusion coefficient of anodic reaction components showed a first decrease and then increase trend when the pH increased. And the diffusion coefficient reached the maximum value of 3.11 × 10−3 cm2∙s−1 at pH of 13.98, which was favorable for accelerating the diffusion of reaction components from the bulk solution to the electrode surface. This work can provide guidance for further improving the diffusion of reaction components, the biochar oxidation rate and hydrogen production in BAWE process. [ABSTRACT FROM AUTHOR]

• The condensation heat transfer characteristics of R410A on the outside of three enhanced tubes were experimentally investigated. • Effect of surface structure, mass flux, average vapor quality, and saturation temperature on HTC and frictional pressure drop. • The six correlations are evaluated and the correlation with the highest accuracy is selected and modified to obtain a predictive correlation suitable for the enhanced tubes. Condensation heat transfer characteristics on the outer annular walls of double-sided horizontal tubes having three different enhancement geometries are investigated experimentally. The enhancement geometries are (1) a fine fin array, (2) a rectangular convex platform array, and (3) a T-shaped column array. The inner surface geometries are threads of various pitches. The experiments are with various mass fluxes, average vapor qualities, and saturation temperatures. They were conducted with refrigerant R410A. The results show the effects of enhancement geometry. Six correlations are used to predict the heat transfer coefficients of smooth tube, and the correlation with the highest accuracy is selected and corrected to obtain a new correlation suitable for the enhanced tubes. The new correlation can predict 92% of the data points within a prediction error of +22% to -30%. Frictional pressure drops are correlated with mass flux, average vapor quality, and saturation temperature. The heat transfer performances of the three experimental tubes are compared using a performance evaluation factor and the enhancement geometries with better condensation heat transfer performances are identified. [ABSTRACT FROM AUTHOR]

• Electric vehicle driving conditions and component working modes are identified. • An assessment method for thermal management system adaptability is proposed. • Experiments verify the system performance and the evaluation method's feasibility. • An integrated thermal management system with waste heat recovery and utilization is designed. • The waste heat utilization vapor compression heat pump system improves mileage effectively. Concerns about the driving ranges of electric vehicles (EV) have led to higher requirements for vehicle thermal management systems. Efficient thermal management systems should be closely integrated with the vehicle to ensure passenger comfort and maintain adequate component operating ranges. The thermal management functions should thus accurately meet the demands of the EV and its components. Based on the driving conditions for EVs and the component thermal management requirements, this study applies different working modes for the cabin, power battery, electric motor, and electric motor controller systems under various conditions, which combines these modes into 27 feasible system working modes. Subsequently, an integrated thermal management system is designed with multi-modes adjusted by each system component to adapt environmental variations by changing the system's working mode. Also, the energy exchange between components under different modes was investigated to ensure the rationality of the designed system. The best working mode is to ensure the safety and comfort for EVs with fewer components and lower cost. It was proved to meet a wide range of adaptations to environmental changes that can be used as a method to evaluate the integrated thermal management system. The method is then applied to the target thermal management system and proves that the target system offers considerable advantages over two other benchmark thermal management systems that have been used in the mass production of electric vehicles. Finally, the cooling, heating, and defrosting performances are verified experimentally, and the vehicle mileage is calculated. The thermal management system working modes are summarized systematically. The designed thermal management system is a waste heat recovery steam compression heat pump system that can meet the functional and experimental test requirements. This study verifies that the heat management system evaluation method can evaluate the system's applicability effectively and that the waste heat utilization vapor compression heat pump system can effectively improve electric vehicle driving mileage, which manifests the potential for mass production for electric vehicle applications. [ABSTRACT FROM AUTHOR]

Dewatering of sewage sludge (SS) was the prerequisite for saving its drying energy and sustaining its stable combustion. Hydrothermal treatment (HT) has been a promising technology for improving SS dewaterability with high energy efficiency. However, the knowledge of phosphorus (P) transformation and heavy metals (HMs) behaviors in the combined HT and incineration process was still lack. P fractions, P-bioavailability, HMs speciation, and their environmental risk in the ash samples from this combination process were evaluated and compared with those from the co-incineration of SS and CaO. The combination process was superior to the latter one in the light of P and HMs. CaO preferred to enhance the transformation of non-apatite inorganic phosphorus (NAIP) to apatite phosphorus (AP) initially with enriched P and increased P-bioavailability in the resultant ash samples. The combination process further reduced the values of risk assessment code and individual contamination factor with the increment of the stable F4 fraction in HMs. Significant reduction of potential ecological risk was observed with the lowest global risk index of 43.76 in the combination process. Optimum CaO addition of 6% was proposed in terms of P and HMs. The work here can provide theoretical references for the potential utilization of P from SS to mitigate the foreseeable shortage of P rocks. [Display omitted] • Hydrothermal treatment combined with incineration of sewage sludge was studied. • P enrichment and bioavailability in ash were enhanced by combination process. • Reduced mobility and ecological risk of heavy metals were observed in ash. • Combination process was superior to co-incineration of sewage sludge and CaO. • CaO preferred to enhance the transformation of NAIP to AP in combination process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Photocatalyst (ACW) for 4-NP reduction is facilely synthesized via in-situ redox. • In ACW, Au and Cu NPs are loaded on Cu wire surface with submicro-sized Cu cubes. • ACW has a large specific surface area and a high loading density of Au and Cu NPs. • ACW exhibits superior photocatalytic activity, reusability and stability. • In-situ redox provides a novel route to prepare metal NPs-supported bulk catalysts. Based on a normal copper wire, an effective photocatalyst (ACW) for the 4-nitrophenol (4-NP) reduction is successfully synthesized by an in-situ redox method. The constitution of ACW is similar to "ants on a tree", i.e., dense Au and Cu nanoparticles (NPs) are loaded on the copper wire surface covered by submicro-sized Cu cubes. Employing ACW as photocatalyst, the conversion efficiency of 4-NP can achieve to 100% at 2.5 min and the rate constant for the 4-NP reduction can reach up to 1.45 min−1. Moreover, ACW exhibits satisfactory reusability for 25 cycles and stability in 12 months. These excellent performance can be attributed to the synergistic effect of Au NPs, Cu NPs and the Cu wire surface covered with submicro-sized cubes. Clearly, the above in-situ redox method provides a facile route to prepare metal NPs-supported bulk photocatalysts. Meanwhile, as-synthesized ACW can be a promising photocatalyst candidate for the practical treatment of 4-NP. [ABSTRACT FROM AUTHOR]

• A greater proportion of copper metal foam (CMF) can enhance the heat transfer of paraffin wax and reduce the temperature gradient. • A theoretical model was built to calculate the comprehensive heat transfer coefficient of composite PCMs and to determine the intensity change of heat conduction and natural convection of PCMs with different CMF proportions. • Melting time and heat storage capacity of CMF composite PCMs first increased and then decreased with increasing CMF proportion. • Heat storage rate and comprehensive heat transfer coefficient first decreased and then increased with increasing CMF proportion. • Composite PCMs with a CMF proportion of 0.86% exhibit the best heat storage performance. Phase-change materials (PCMs) can overcome the low energy density and utilization efficiency of solar energy. However, the low thermal conductivity of PCMs significantly affects the thermal efficiency of solar devices; thus, improving the thermal conductivity of PCMs has been the focus of many recent studies. In this study, copper metal foam (CMF) composite PCMs were prepared using paraffin wax and high-pore-density CMF. The effect of the CMF proportion on heat transfer enhancement in the PCM melting process was analyzed using experimental equipment for heat storage visualization. Comprehensive heat transfer coefficients of CMF composite PCMs were obtained. The experimental results showed that as the CMF proportion increased from 0 to 2.15%, the melting time of the CMF composite PCMs and their heat storage capacity first increased and then decreased, whereas the heat storage rate and comprehensive heat transfer coefficient first decreased and then increased. The minimum temperature gradient of 8.09 K was reached when the CMF proportion was 2.15%. More importantly, as the proportion of CMF increased from 0.43 to 2.15%, the proportion of natural convection decreased from 87.90 to 17.69%, and natural convection was the major heat transfer mechanism in the melting process of composite PCMs with a low CMF proportion. The composite PCMs with a CMF proportion of 0.86% has the best heat storage performance when the heat storage capacity and heat storage rate were both considered. [ABSTRACT FROM AUTHOR]

The SO 2 -depolarized electrolysis (SDE) is one of the main processes in the hybrid sulfur cycle for hydrogen production, the microscopic characteristics of which are still not clear. In this work, a numerical analysis of SDE was conducted. The steady-state, laminar and incompressible 2D model of the electrolytic cell (EC) for carrying out SDE was first developed and verified. Physical field characterization indicated that the velocity was almost uniformly distributed in the flow channel, but higher pressure drops and pumping power consumption existed in the anode channel than in the cathode channel. Meanwhile, the continuous conversion of SO 2 to H 2 SO 4 at anode and generation of H 2 at cathode along the channel length were determined. Further exploring the impacts of three main operating parameters implied that an appropriate higher electrolytic potential, lower inlet flow rate (not less than 0.005 m/s) and operating temperature were favorable for improving the SDE. After comprehensive consideration of SDE performance and energy consumption, a feasible operating condition of 0.8 V, 303 K, and 0.005 m/s was proposed for SDE process. The developed model and microscopic characterization of SDE will favor the design and optimization of EC for SDE process. [Display omitted] [ABSTRACT FROM AUTHOR]

Biochar-assisted water electrolysis (BAWE) for hydrogen production is an effective way to integrate renewable electricity and biomass utilization. But it is limited by slow biochar oxidation reaction (BOR). Here we adopted the biochar derived from pyrolysis (PB) and hydrothermal carbonization (HB) of rice husk. Replacement of oxygen evolution reaction with BOR leaves a significantly reduced onset potential (E onset) and an increased current density. Strongly related to carbonization temperature, the physicochemical properties of biochar markedly affected BOR. The abundant –OH groups in HB contributed to a low E onset , while the well-developed pore structure and high specific surface area of PB enhanced its reactivity at higher potential. Exposure of functional groups on PB surface after pickling made an increase in current density, but the simultaneous elimination of easily oxidized solutes in HB dominated and caused current density decline. H 2 SO 4 electrolyte of 1 mol/L was most appropriate for the uniform dispersion of biochar particles. The oxidation of PB derived at 800 °C with a slurry concentration of 10 g/L showed the lowest charge-transfer resistance and a favorable kinetics. Continuous BAWE indicated that PB was more superior than HB in increasing current density and H 2 production. This work provides favorable strategies for improving BAWE. [Display omitted] • Biochar derived from rice husk was used for biochar-assisted water electrolysis. • Anodic biochar oxidation reaction (BOR) was more energy-efficient than OER. • Relationships between physicochemical properties and BOR were characterized. • Pyrolytic biochar possess superiority in increasing current density and H 2 production. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe2+/Fe3+ or N O 2 - / N O 3 - mediated biochar-assisted water electrolysis was studied. • Biochar oxidation reaction (BOR) was enhanced with ions mediation. • Mechanism of anodic oxidation reaction with mediator was deduced. • The activation energy of BOR was reduced by 33.9% and 58.5% with Fe2+ and N O 2 - mediation. The biochar-assisted water electrolysis (BAWE) is a promising method for clean biomass utilization and hydrogen production. But it is limited by the slow anode biochar oxidation reaction (BOR). To enhance the BOR, the mediator of Fe2+/Fe3+ or N O 2 - / N O 3 - was added to the pyrolytic biochar (PB) and tested using electrochemical methods. Both Fe2+ and N O 2 - showed stronger oxidation activity than Fe3+ and N O 3 - , and thereby presented more significant enhanced role on BOR, including the reduction in onset potential and the enlargement of current density. Fe2+/Fe3+ existence resulted in the five-step mechanism such as adsorption, redox reaction in solution, oxidation at electrode surface, and passive films formation on the biochar surface. 0.5 mol/L or less of Fe2+/Fe3+ was suggestable, while the lower acid concentration was necessary to avoid side reaction with N O 2 - existence. The Fe2+/Fe3+ acted as catalysts due to the almost unchanged total iron ions during continuous BAWE process, whereas a high consumption of N O 2 - occurred. The cathode hydrogen production was less influenced by mediator and showed comparable with the theoretical value of Faraday's law. In addition, the activation energy of BOR was significantly reduced with Fe2+ and N O 2 - mediation. The present work provides a favorable strategy for improving BOR and energy-saving production of hydrogen via BAWE process. [ABSTRACT FROM AUTHOR]